1h-imidazo(4,5-b)pyridine derivatives

ABSTRACT

Ethers and esters of 1-hydroxy-2-(1,1-difluoroalkyl)-1H-imidazo(4,5-b)pyridine compounds, useful as herbicides.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a division of my copending application Ser. No. 447,115, filed Mar. 1, 1974 and issued May 8, 1976, as U.S. Pat. No. 3,961,937, which was in turn a division of my then copending application Ser. No. 236,195, filed Mar. 20, 1972, and issued June 18, 1974, as U.S. Pat. No. 3,818,022. Application Ser. No. 236,195 was, in turn, a continuation-in-part of my then copending application Ser. No. 181,638, filed Sept. 17, 1971, and abandoned after the filing of application Ser. No. 236,195. Application Ser. No. 181,638 was, in turn, a continuation-in-part of my then copending application Ser. no. 100,410, filed Dec. 21, 1970, and abandoned after the filing of application Ser. No. 181,638 abandoned.

SUMMARY OF THE INVENTION

The present invention is direction to ethers and esters of 1-hydroxy-2-(1,1-difluoroalkyl)-1H-imidazo( 4,5-b)pyridine compounds. These derivatives are of the following formula: ##STR1## In the above and succeeding formulae throughout the present specification and claims, R¹ represents hydrogen, chlorine, fluorine, difluoromethyl, perfluoroalkyl of C₁ -C₆, or radical of the formula ##STR2## wherein each Z independently represents hydrogen or halogen and m represents 0 or 1; R² represents amino, halogen, nitro, cyano, loweralkyl of C₁ -C₄, perfluoroalkyl of C₁ -C₈, --CF₂ Cl, --CF₂ H, or loweralkylsulfonyl of C₁ -C₄, subject to the limitations (1) that all R² substituents together contain not more than 8 carbon atoms; (2) that not more than two R² symbols represent loweralkylsulfonyl groups; and (3) that where two loweralkylsulfonyl groups are present, they are located at the 5- and 7-positions; n represents an integer of from 1 to 3, both inclusive; and R³ represents

(1) ALKYL OF C₁ -C₈ ;

(2) alkenyl of C₂ -C₈ ;

(3) cycloalkyl of C₅ -C₆ ;

(4) benzyl;

(5) PHENETHYL;

(6) ALKANOYL OF C₂ -C₁₆ ;

(7) alkenoyl of C₃ -C₁₆ :

(8) carbamoyl of the formula ##STR3## wherein X represents oxygen or sulfur; and one R⁴ represents phenyl, loweralkyl of C₁ -C₄, or loweralkenyl of C₂ -C₄, and the other R⁴ represents hydrogen, loweralkyl of C₁ -C₄, or loweralkenyl of C₂ -C₄, subject to the limitation that both R⁴ moieties taken together do not contain more than six carbon atoms, or both R⁴ moieties taken together represent straight-chain alkylene of C₂ -C₆, both inclusive;

(9) radical of the formulae ##STR4## of C₁ -C₄ or ##STR5## wherein X is, as above, oxygen or sulfur.

(10) radical of the formula ##STR6## wherein R⁵ represents methylene, ethylene, or vinylene, and n represents 0 or 1;

(11) radical of the formulae ##STR7## phenyl and ##STR8## phenyl, wherein substituted phenyl is a phenyl radical bearing from 1-3 substituents, each or which is independently amino, nitro, chloro, methyl, or methoxy, and R⁶ represents loweralkylene of C₁ -C₄, both inclusive;

(12) --SO₂ --R⁷ wherein R⁷ is loweralkyl as above defined, cycloalkyl of C₅ -C₆, phenyl, substituted phenyl as above defined, or benzyl;

(13) tetrahydro-2-pyranyl.

The compounds so defined are useful as herbicides. In addition, they can be used as starting materials for a process which results in rearrangement or reduction depending on the reaction conditions employed.

DETAILED DESCRIPTION OF THE INVENTION

In the present specification and claims, the term "halogen" is employed to designate bromine, chlorine, fluorine, and iodine, only. In the case of the loweralkyl, loweralkenyl, alkyl, alkenyl, alkanoyl, alkenoyl, and loweralkylene radicals, such radical can be branched or straight-chain.

An essential and distinguishing structural feature of the compounds of the present invention is the substituent at the 2-position (--CF₂ --R¹); representative such radicals include the following:

difluoromethyl

trifluoromethyl

difluorochloromethyl

pentafluoroethyl

heptafluoro-n-propyl

1,1-difluoroethyl

1,1-difluoro-n-propyl

1,1-difluoro-2-bromoethyl

1,1-difluoro-2-chloroethyl

1,1-difluoro-2,3-dichloro-n-propyl

1,1-difluoro-3-bromo-n-propyl

1,1,2-trifluoroethyl

1,1,2-trifluoro-n-propyl

1,1,2,3-tetrafluoro-n-propyl

1,1-difluoro-2-bromo-3-chloro-n-propyl

perfluoro-n-butyl

perfluoro-n-pentyl

perfluoro-n-hexyl

1,1,2,2-tetrafluoroethyl

Preferred groups are trifluoromethyl, difluoromethyl, difluorochloromethyl, 1,1,2,2-tetrafluoroethyl, and pentafluoroethyl.

The compounds of the present invention are typically crystalline solids. They are prepared in standard procedures for the derivatization of hydroxy groups. Hence, those of the derivatives claimed herein which are ethers can be prepared by those procedures discussed in chapter 6 of Synthetic Organic Chemistry, by Wagner and Zook (John Wiley and Sons, Inc., New York, 1965). The same reference discusses various synthetic procedures which can be employed for the synthesis of those derivatives claimed herein which are carboxylic acid esters (chapter 14), carbamic acid esters (chapter 23), and sulfonic acid esters (chapter 37).

Generally, the compounds of the present invention are conveniently prepared by the reaction of the corresponding 1-hydroxy compounds: ##STR9## with a halide of the formula R³ -X, where X is halo, in the presence of an alkali metal carbonate or other hydrogen halide acceptor. An inert liquid reaction medium can be used. The reaction proceeds under a wide range of temperatures, but is preferably conducted at temperatures of from -20° C. to the reflux temperature. Separation, and if desired, purification, are carried out in conventional procedures.

While the foregoing is the most general method, other methods are convenient and may be preferred for some of the compounds. Thus, those carbamates of the formula ##STR10## are more readily prepared by reacting the corresponding 1-hydroxy-1H-imidazo(4,5-b)pyridine with an isocyanate of the formula

    O═N═C═loweralkyl or loweralkenyl

The reaction is conducted in conventional procedures.

Likewise, the carboxylic ester compounds of the present invention other than the carbamate esters are often preferably prepared by reacting the desired carboxylic acid as its anhydride with the corresponding 1-hydroxy-1H-imidazo(4,5-b)pyridine starting compound. Furthermore, in the case of the present compounds which are ethers, preparation is sometimes preferably carried out by reaction of the 1-hydroxy-1H-imidazo(4,5-b)pyridine with an olefin; this is particularly preferred in the case of the tetrahydro-2-pyranyl ether. The alkenyl ethers may also be preferably prepared by addition to an alkyne.

Yet other synthetic techniques can be used in the preparation of the compounds of the present invention; examples are the use of N,N'-carbonyldiimidazole or N,N'-dicyclohexyldicarbodiimide (See Reagents for Organic Synthesis, Fieser and Fieser (John Wiley and Sons, 1967), pages 114 et seq. and 231 et seq., respectively.

The following examples illustrate the present invention and will enable those skilled in the art to practice the same.

EXAMPLE 1

1-METHOXY-6-CHLORO-2-(TRIFLUOROMETHYL)-1H-IMIDAZO(4,5-b)PYRIDINE

1-Hydroxy-6-chloro-2-(trifluoromethyl)-1H-imidazo-(4,5-b)pyridine (5 grams), 80 milliliters of acetone, 5 milliliters of methyl iodide, and 10 grams of anhydrous potassium carbonate were mixed, heated and refluxed with stirring for twelve hours. The reaction mixture was then filtered, evaporated and eluted off of a silica column with diethyl ether, yielding the desired 1-methoxy-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine product. It was recrystallized from petroleum ether (boiling at 60°-80° C.). The product so obtained melted at 91°-2° C.

Analysis, Calc.: C, 38.20; H, 1.99; N, 16.70. Found: C, 37.92; H, 2.32; N, 16.75.

EXAMPLE 2

1-BENZYLOXY-6-CHLORO-2-(TRIFLUOROMETHYL)-1H-IMIDAZO(4,5-b)PYRIDINE

1-Hydroxy-6-chloro-2-(trifluoromethyl)-1H-imidazo-(4,5-b)pyridine (5 grams), 10 milliliters of benzyl bromide, 20 grams of anhydrous potassium carbonate, and 100 milliliters of ethanol were mixed, heated to reflux, and refluxed for one hour. The reaction mixture was then filtered, evaporated under vacuum, and extracted with diethyl ether. The extract was filtered and evaporated under vacuum yielding a dark oil which on standing crystallized as the desired 1-benzyloxy-6-chloro-2-(trifluoromethyl)- 1H-imidazo(4,5-b)pyridine. It was recrystallized from a mixture of acetone and petroleum ether boiling at 60°-80° C., m.p., 107°-09° C.

Analysis, Calc.: C, 51.31; H, 2.77; N, 12.82. Found: C, 51.54, H, 2.62; N, 13.12.

EXAMPLE 3

1-ACETOXY-6-CHLORO-2-(TRIFLUOROMETHYL)-1H-IMIDAZO(4,5-b)PYRIDINE

1-Hydroxy-6-chloro-2-(trifluoromethyl)-1H-Imidazo(4,5-b)pyridine (5 grams), 25 milliliters of acetic anhydride and 0.1 milliliter of sulfuric acid were mixed with stirring at 25° C. for fifteen minutes. The reaction mixture was then heated to reflux and refluxed for one-half hour, poured into ice with stirring, stirred for ten minutes and filtered. Filtration yielded the desired 1-acetoxy-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine product as a solid. It was taken up in ether, dried over magnesium sulfate, and the ether evaporated. The product then melted at 103°-04° C.

Analysis, Calc.: C, 38.65; H, 1.80; N, 15.02. Found: C, 38.88; H, 1.92; N, 15.02.

EXAMPLE 4

1-OCTANOYLOXY-6-CHLORO-2-(TRIFLUOROMETHYL)1H-IMIDAZO(4,5-b)PYRIDINE

To 1-hydroxy-6-chloro-2-(trifluoromethyl)-1H-Imidazo(4,5-b)pyridine (2.37 grams) in 5 milliliters of pyridine was added octanoyl chloride (1.63 grams). The addition was carried out portionwise with stirring and resulted in the precipitation of a white solid. The reaction mixture was set on a steam bath for twenty minutes, then poured over ice cold aqueous HCl. An oil separated and subsequently crystallized on vigorous stirring. This precipitate was removed by filtration, dissolved in ether, dried over magnesium sulfate, filtered, and ether removed by evaporation under vacuum. The substance was purified by distillation, m.p., 33.5°-35.5° C.

Analysis, Calc.: C, 49.52; H, 4.71; N, 11.55. Found: C, 49.81; H, 4.93; N, 11.29.

EXAMPLE 5

1-(ALLYLCARBAMOYLOXY)-6-CHLORO-2-(TRIFLUOROMETHYL)- 1H-IMIDAZO(4,5-b)PYRIDINE

1-Hydroxy-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine (4.6 grams) was dissolved in 10 milliliters of diethyl ether and 2.4 milliliters of allyl isocyanate added and the reaction mixture stirred at room temperature for thirty-six hours. The reaction mixture was then filtered yielding 4.75 grams of a white powder, the desired 1-(allylcarbamoyloxy)-6 -chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine. An additional portion of the product was obtained by evaporating the filtrate. The combined products were recrystallized from a mixture of diethyl ether and petroleum ether boiling at 60°-80° C., m.p., about 210° C.

Analysis, Calc.: C, 41.20; H, 2.51; N, 17.47. Found: C, 41.42; H, 2.51; N, 17.25.

EXAMPLE 6

1-(METHYLSULFONYLOXY)-6-CHLORO-2-(TRIFLUOROMETHYL)- 1H-IMIDAZO(4,5-b)PYRIDINE

1-Hydroxy-6-chloro-2-(trifluoromethyl)-1H-imidazo-(4,5-b)pyridine (5 grams) in 15 milliliters of pyridine was cooled to 5° C. with stirring and methylsulfonyl chloride (5 milliliters) was added in 1-milliliter portions, maintaining the temperature at about 5° C. After the addition was completed, the reaction mixture was stirred for two hours at 5°-10° C., then poured into 30 grams of ice and 20 milliliters of concentrated hydrochloric acid. The desired 1-(methylsulfonyloxy)-6-chloro-2-(trifluoromethyl)- 1H-imidazo(4,5-b)pyridine product precipitated and was separated by filtration and washed with water. The washed product was taken up in diethyl ether with a trace of acetone, dried over magnesium sulfate and the solvent evaporated under vacuum. The product so obtained melted at 136.7° C.

Analysis, Calc.: C, 30.44; H, 1.60; N, 13.31. Found: C, 30.48; H, 1.83; N, 13.00.

EXAMPLE 7

1-METHOXY-6-AMINO-5,7-DIBROMO-2-(TRIFLUOROMETHYL)-1H-IMIDAZO(4,5-b)PYRIDINE

6-Amino-5,7-dibromo-2-trifluoromethyl-1-hydroxy-1H-imidazo(4,5-b)pyridine (1 gram) was mixed and stirred for two hours with 2 milliliters of methyl iodide, 2 grams of potassium carbonate, and 10 milliliters of acetone. The reaction mixture was then diluted with about 80 milliliters of ether and washed with five 15-milliliter portions of water. The ether layer was dried over magnesium sulfate and filtered with carbon, and the ether removed on a rotary evaporator. The resulting 1-methoxy-6-amino-5,7 -dibromo-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine product melted at 169°-72° C. A portion was recrystallized from methanol, m.p., 177°-8° C.

Analysis, Calc.: C, 24.64; H, 1.29; N, 14.37. Found: C, 24.96; H, 1.51; N, 14.48.

EXAMPLE 8

1-(METHYLCARBAMOYLOXY)-6-CHLORO-5,7-DIBROMO-2 -(TRIFLUOROMETHYL)-1H-IMIDAZO(4,5-b)PYRIDINE

6-Chloro-5,7-dibromo-1-hydroxy-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine (0.9 gram) was mixed with ether (15 milliliters) and methyl isocyanate (2 milliliters) and stirred for fifteen minutes. Triethylamine (0.01 milliliter) was added, and the solution became homogenous. It was permitted to stand for sixteen hours, diluted with 50 milliliters diethyl ether; washed with 0.5N HCl, water, and saturated NaCl; then dried over magnesium sulfate, and evaporated. The resulting 1-(methylcarbamoyloxy)-6 -chloro-5,7 -dibromo-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine product was recrystallized from chloroform, m.p., 216° C.

Analysis, Calc.: C, 23.89; H, 0.89; N, 12.38. Found: C, 23.82; H, 0.90; N, 12.16.

EXAMPLES 9-61

Other representative compounds of the present invention, prepared in accordance with the foregoing teachings, include the following:

1-allyloxy-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine, n_(D) ²³.5 1.5204.

1-isopropoxy-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)-pyridine, m.p., 49°-51° C.

1-ethoxy-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine, n_(D) ²⁵ 1.5082.

1-(methylcarbamoyloxy)-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine, m.p., 267° C.

1-(2-methoxy-3,6-dichlorobenzoyloxy)-6-chloro-2-(trifluoromethyl) -1H-imidazo(4,5-b)pyridine, m.p., 148°-9° C.

1-ethoxy-2,6-bis(trifluoromethyl)-1H-imidazo(4,5-b)-pyridine, n_(D) ²⁵ 1.5100.

1-methoxy-6-nitro-2-(trifluoromethyl)-1H-imidazo(4,5-b)-pyridine.

1-n-octyloxy-6-(methylsulfonyl)-2-(heptafluoro-n-propyl)- 1H-imidazo(4,5-b)pyridine.

1-n-butoxy-6-fluoro-2-(1,1-difluoroethyl)-1H-imidazo(4,5-b)-pyridine.

1-phenethoxy-2,6-bis(chlorodifluoromethyl)-1H-imidazo(4,5-b)-pyridine.

1-vinyloxy-2,6 -bis(difluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-(dimethylcarbamoyloxy)-6-bromo-2-(perfluoro-n-hexyl)-1H-imidazo(4,5-b)pyridine.

1-methacryloyloxy-6-chloro-2-(trifluoromethyl)-1H-imidazo-(4,5-b)pyridine.

1-lauroyloxy-2,6-bis(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-(2,4-dichlorophenoxyacetoxy)-6-chloro-2-(trifluoromethyl)- 1H-imidazo(4,5-b)pyridine.

1-benzoyloxy-2,6-bis(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-(phenylacetoxy)-6-chloro-2-(trifluoromethyl)-1H-imidazo-(4,5-b)pyridine.

1-(3-phenylpropionyloxy)-6-(methylsulfonyl)-1H-imidazo-(4,5-b)pyridine.

1-cinnamoyloxy-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)-pyridine.

1-(3-(2,4,5-trichlorophenoxy)propionyloxy)-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-cyclohexyloxy-6-chloro-2-(trifluoromethyl)-1H-imidazo-(4,5-b)pyridine.

1-(phenylsulfonyloxy)-2,6-bis(difluoromethyl)-1H-imidazo(4,5-b)-pyridine.

1-(benzylsulfonyloxy)-6-chloro-2-(difluoromethyl)-1H-imidazo-(4,5-b)pyridine.

1-(cyclohexylsulfonyloxy)-6-nitro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-((p-chlorophenyl)sulfonyloxy)-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-(2-butenyloxy)-6-(isopropylsulfonyl)-2-(1,1-difluoro-3-chloropropyl)-1H-imidazo(4,5-b)pyridine.

1-(6-octenyloxy)-6-chloro-2-(trifluoromethyl)-1H-imidazo-(4,5-b)pyridine.

1-(9-hexadecenoyloxy)-6-chloro-2-(trifluoromethyl)-1H-imidazo-(4,5-b)pyridine.

1-(isopropylthiocarbamoyloxy)-6-chloro-2-(pentafluoroethyl)-1H-imidazo(4,5-b)pyridine.

1-(3-amino-2,5-dichlorobenzoyloxy)-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-(2,5-dichloro-3-nitrobenzoyloxy)-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-(2-(4-chloro-o-tolyloxy)acetoxy)-2,6-bis(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-(tetrahydro-2-pyranyloxy)-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-methoxy-2,6-bis(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-(methylcarbamoyloxy)-2,6-bis(trifluoromethyl)-1H-imidazo-(4,5-b)pyridine.

1-(2-methoxy-3,6-dichlorobenzoyloxy)-6-amino-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-(methylsulfonyloxy)-6-nitro-5,7-dibromo-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-(2-(4-chloro-o-tolyloxy)acetoxy)-5-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-(2,4-dichlorophenoxyacetoxy)-7-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-methoxy-5-(methylsulfonyl)-2-(pentafluoroethyl)-1H-imidazo-(4,5-b)pyridine.

1-ethoxy-7-fluoro-2-(difluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-propionyloxy-5-chloro-6-bromo-2-(1,1,2,2-tetrafluoroethyl)-1H-imidazo(4,5-b)pyridine.

1-octanoyloxy-7-amino-2-(difluorochloromethyl)-1H-imidazo(4,5-b)-pyridine.

1-methoxy-7-nitro-2-(difluorochloromethyl)-1H-imidazo(4,5-b)-pyridine.

1-allyloxy-2,7-bis(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-cyclohexyloxy-5,6,7-trinitro-2-(trifluoromethyl)-1H-imidazo-(4,5-b)pyridine.

1-benzyloxy-5,6,7-trichloro-2-(difluoromethyl)-1H-imidazo(4,5-b)-pyridine.

1-phenethoxy-5,6-bis(difluoromethyl)-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-acetoxy-2,5,6-tris(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-acryloyloxy-5,6-bis(difluorochloromethyl)-1H-imidazo(4,5-b)-pyridine.

1-(tetrahydro-2-pyranyloxy)-5,6-bis(ethylsulfonyl)-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-benzoyloxy-6-methyl-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.

1-methoxy-6-(perfluorooctyl)-2-(trifluoromethyl)-1H-imidazo(4,5-b)-pyridine.

The compounds of the present invention are adapted to be employed as herbicides. The compounds can be utilized to achieve broad herbicidal action; hence, in its broadest sense, the present invention is directed to a method which comprises applying to a plant part, which can be a stem, leaf, flower, fruit, root, or seed or other similar reproductive unit of a plant, a growth-inhibiting amount of one of the compounds of the present invention. However, the compounds can also be utilized to take advantage of selective patterns of herbicidal activity.

It is not critical to the practice of the present invention that complete destruction of undesirable vegetation be obtained, it being adequate if the growth of the unwanted vegetation is merely inhibited. Especially where selective action is sought, inhibition falling short of actual killing is adequate, particularly when combined with naturally occurring conditions such as limited moisture and the like which more adversely affect the vegetation selectively inhibited than the crop plant.

The compounds of the present invention are suited to a wide variety of herbicidal applications. Thus, for example, at rates which evoke the selective action of the compounds, which rates are defined more completely hereinbelow, the compounds can be used as selective herbicides in crop plants, such as, for example, cotton, corn, sorghum, soybeans, and the like. In such use, application can be made preemergent to both crops and weeds, or, preferably by means of a directed spray application technique postemergent to the crop plant but both preemergent and postemergent to the weeds. In another application, the compounds can be used to give broad herbicidal action on non-crop land, including intermittently non-crop strips of contour-farmed land. For such usage on so-called fallow land, application can be made in spring to suppress vegetative growth until a fall or following spring planting, or in the fall to suppress vegetative growth until a spring or following fall planting. Furthermore, in another application, the present compounds can be utilized to control weeds in tree crop plantings, such as plantings of the various citrus trees. In all of these various applications, and yet others for which the present compounds are suited, another advantage is that the compounds need not be disced into the soil being treated, it being adequate if one of the compounds, or a formulation containing one of the compounds, is merely spread onto the top surface. However, where desired or convenient, the compounds can be disced into, or otherwise mechanically mixed with the soil. In addition to the foregoing terrestrial embodiments, the present compounds can also be utilized as aquatic herbicides.

The practice of the present invention in any of its numerous embodiments can in some instances be carried out with unmodified compound; however, for good results, it is generally necessary that the compound be employed in modified form, that is, as one component of a composition formulated to implement the plant growth-inhibiting effects. Thus, for example, the active agent can be mixed with water or other liquid or liquids, preferably aided by the usage of a surface active agent. The active agent can also be incorporated on a finely divided solid, which can be a surface active substance, to yield a wettable powder, which can subsequently be dispersed in water or other liquid, or incorporated as part of a dust which can be applied directly. Other methods of formulations are known in the art and can be employed in implementing the present invention.

In carrying out the novel method of the present invention, the exact amount of the active agent employed is not critical and will vary, depending upon the type of growth-inhibiting effect desired, the identity of the plants concerned, the particular active agent used, weather conditions, and the like. In general, a broad growth-inhibiting effect is obtained with rates of from 3-5 to 20 pounds or more of active agent per acre, and such rates are suitable and effective for control of vegetative growth on fallow land. When it is desired to obtain a selective growth-inhibiting effect on weeds in areas containing crop plants such as corn, soybeans, and cotton, rates of from 0.25 or less to 5 pounds generally give good results. When in the typical mode of operation, the active agent is employed as a composition comprising the agent, the exact concentration of active agent in the composition is not critical, except that the concentration and total amount of formulation employed be adequate to supply the appropriate amount of active agent on a per acre basis. In general, good results are obtained when employing formulations containing the active agent in a concentration of from 0.5 to 10 percent or higher, in the instance of a liquid formulation; and in a concentration of from 1.0 to 5.0 percent or higher, in the instance of a dust, powder, granule, or the like. More concentrated formulations can be prepared and are often preferred in that they can serve, depending upon the particular application contemplated and the particular concentration, both as a concentrated formulation for purposes of shipment, storage, and the like, and as an ultimate treating composition. Thus, for example, formulations often preferably contain a surface active agent and the present active agent, the latter being present in an amount of from 0.5 to 99.5 percent, by weight; or an inert, finely divided solid and the present active agent, the latter being present in an amount of from 1.0 to 99.0 percent, by weight. Such formulations, as indicated, can be employed directly in certain applications, but can also be diluted and subsequently employed in many other applications.

Liquid compositions containing the desired amount of active agent are prepared by dissolving the substance in a liquid with or without the aid of a surface active dispersing agent such as, an ionic or non-ionic emulsifying agent. Most preferably, the subject compound is dissolved in water or in an organic liquid carrier, aided by the use of a surface active dispersing agent. Suitable such organic liquid carriers include agricultural spray oils and the petroleum distillates such as diesel fuel, kerosene, fuel oil naphthas and Stoddard solvent. The choice of dispersing and emulsifying agent and the amount thereof employed is dictated by the nature of the composition and by the ability of the agent to facilitate the dispersion of the active agent in the carrier to produce the desired composition. Dispersing and emulsifying agents which can be employed in the compositions include the condensation products of alkylene oxides with phenols and organic acids, alkyl aryl sulfonates, polyoxyalkylene derivatives or sorbitan esters, complex ether alcohols, and the like. Representative surface active agents which are suitably employed in implementing the present invention are identified in U.S. Pat. Nos. 3,095,299, second column, lines 25-36, 2,655,447, column 5, and 2,412,510, columns 4 and 5.

In the preparation of dust compositions, the active ingredient is intimately dispersed in and on a finely divided solid such as clay, talc, chalk, gypsum, limestone, vermiculite fines, perlite, and the like. In one method of achieving such dispersion, the finely divided carrier is mechanically mixed or ground with the active agent.

Similarly, dust compositions containing the toxicant compounds can be prepared with various of the solid surface active dispersing agents such as bentonite, fuller's earth, attapulgite and other clays. Depending upon the proportions of ingredients, these dust compositions can be employed as concentrates and subsequently diluted with additional solid surface active dispersing agents or with chalk, talc, or gypsum and the like to obtain the desired amount of active ingredient in a composition adapted to be employed for the suppression of the growth of the plants. Also, such dust compositions can be dispersed in water, with or without the aid of a dispersing agent, to form spray mixtures.

Formulations containing the present active agent are often advantageously further modified by incorporation therein of an effective amount of a surfactant which facilitates the dispersion and spreading of the formulation of the plant leaf surfaces and the incorporation of the formulation by the plant.

In accordance with the present invention, the active agent can be dispersed in soil or other growth media in any convenient fashion. Applications can be carried out by simply mixing with the media, by applying to the surface of soil and thereafter dragging or discing into the soil to the desired depth, or by employing a liquid carrier to accomplish the penetration and impregnation. The application of spray and dust compositions to the surface of soil, or to plant parts or the above ground surfaces of plants can be carried out by conventional methods, e.g., power dusters, boom and hand sprayers and spray dusters, whether surface or air-borne. However, while such conventional modes of application can be used, they are not required. As above noted, it is an advantage of the present invention that the compounds serving as active agent are active and effective as herbicides when merely placed on the surface of the soil, without any additional step to assist incorporation. Thus, the compounds are of substantially the same efficacy regardless of whether they are applied to the surface only, or whether they are applied to the surface and subsequently disced into the soil.

In a further method, the distribution of the active agent in soil can be accomplished by introducing the agent into the water employed to irrigate the soil. In such procedures, the amount of water is varied with the porosity and water holding capacity of the soil to obtain a desired depth of distribution of the agent.

In addition, the present invention method also comprehends the employment of an aerosol composition containing one or more of the present active agents as an active compound. Such a composition is prepared according to conventional methods wherein the agent is dispersed in a solvent, and the resultant dispersion mixed with a propellant in liquid state. Such variables as the particular agent to be used and the nature of the vegetation which is to be treated will determine the desirability of the solvent and concentration of the agent therein.

Satisfactory results are obtained when the active agent of the present invention, or a composition comprising such active agent, is combined with other agricultural materials intended to be applied to plants, plant parts, or their habitats. Such materials include fertilizers, fungicides, nematocides, insecticides, other herbicides, soil conditioning agents, and the like.

The following further examples illustrate the herbicidal utility of the compounds of the present invention.

EXAMPLES 62-70

Various of the compounds of the present invention were evaluated for preemergent application to various crop and weed species. Each compound was formulated by dissolving it in a 1:1 mixture of acetone and ethanol containing a small amount of a blend of sulfonate nonionic emulsifying agents; the solution was then diluted first with deionized water, then serially with deionized water containing 1000 ppm. of the blend of emulsifiers. The resulting solutions contained the subject compound in various amounts, the emulsifier blend in a concentration of 0.1 percent, and the acetone and ethanol each in a concentration of 4.0 percent.

A soil was prepared consisting of one part masonry sand and one part shredded top soil blended together in a cement mixer. One gallon of this soil was placed in a 21.5 × 31.5 cm. galvanized flat and was patted down with a bench brush until level. A three-row marker was used to make 2 1/2 cm. deep furrows in approximately two-fifths of the flat. Crop seeds consisting of four kernels of corn, five cotton seeds and five soybean seeds were placed in these furrows. A four-row template was then placed on the remaining soil and the indicated approximate numbers of each of the following seeds were planted, one species to each section: foxtail (millet), 80-100 seeds; velvetleaf (40-50 seeds); rough pigweed (150-250 seeds); and large crabgrass (100-150 seeds).

Sufficient soil was added to cover the entire flat. Thus, the weed seeds were covered to a depth of about 6 mm. and the crop seeds were covered to a depth of about 3 cm.

In assaying the effect of the composition as preemergent herbicides, a flat prepared as above, taken either on the day of planting or on the next day, was placed in a chamber equipped with a turntable and an air exhaust. The herbicidal composition was applied to the flat with a modified DeVilbiss atomizer hooked to an air source. Twelve and one-half milliliters of the composition under test were applied to each flat either on the day of planting or on the succeeding day. Injury ratings and observations as to type of injury were made eleven to twelve days after treatment. The injury rating scale used was as follows:

0--no injury

1--slight injury

2--moderate injury

3--severe injury

4--death

When more than one determination was carried out at a given rate, an average value was calculated for the injury rating.

In the following table setting forth the results of the evaluation, column 1 gives the name of the compound under test; column 2, the rate in pounds per acres at which the compound was applied to the test flat; and the remaining columns, the injury to the particular plant seeds or seedlings as measured by the foregoing scale.

                                      TABLE I                                      __________________________________________________________________________     Injury Rating on Preemergent Treatment                                                      Lbs./                         Velvet-                             Compound     Acre                                                                               Corn                                                                              Cotton                                                                             Soybean                                                                             Crabgrass                                                                           Pigweed                                                                             Foxtail                                                                            leaf                                __________________________________________________________________________     1-Methoxy-6-chloro-2-                                                                       8   2  4   3    3    3    4   3                                   (trifluoromethyl)-1H-                                                          imidazo(4,5-b)pyridine                                                                      4   2  2   1    4    4    4   4                                                2   1  1   1    4    3    4   4                                                1   0  1   0    3    3    3   4                                   1-Acetoxy-6-chloro-2-                                                                       8   1  --  --   3    2    3   3                                   (trifluoromethyl)-1H-                                                          imidazo(4,5-b)pyridine                                                                      4   1  0   0    2    2    3   3                                                2   0  0   1    1    2    3   3                                   1-Ethoxy-6-chloro-2-                                                                        8   3  --  --   3    4    4   --                                  (trifluoromethyl)-1H-                                                          imidazo(4,5-b)pyridine                                                                      4   0  0   1    4    3    4   --                                               2   0  0   0    3    2    2   --                                  1-Allyloxy-6-chloro-2-                                                                      8   3  --  --   4    4    4   --                                  (trifluoromethyl)-1H-                                                          imidazo(4,5-b)pyridine                                                                      4   1  0   0    4    3    4   --                                               2   0  0   0    3    1    3   --                                  1-Isopropoxy-6-chloro-2-                                                                    8   2  --  --   4    4    4   --                                  (trifluoromethyl)-1H-                                                          imidazo(4,5-b)pyridine                                                                      4   1  0   1    4    2    4   --                                               2   0  0   0    2    1    3   --                                  1-(Allylcarbamoyloxy-6-                                                                     8   2  --  --   3    3    4   --                                  chloro-2-(trifluoro-                                                           methyl)-1H-imidazo-                                                                         4   0  1   1    3    3    2 --                                    (4,5-b)pyridine                                                                             2   1  2   1    2    0    2   --                                  1-Octanoyloxy-6-chloro-                                                                     8   2  --  --   3    4    4   --                                  2-(trifluoromethyl)-1H-                                                        imidazo(4,5-b)pyridine                                                                      4   1  4   1    4    2    4   --                                  1-(Methylcarbamoyloxy)-                                                                     8   1  --  --   3    3    4   --                                  6-chloro-2-(trifluoro-                                                         methyl)-1H-imidazo-                                                                         4   1  2   1    3    3    4 --                                    (4,5-b)pyridine                                                                             2   0  1   1    1    3    4   --                                  1-Methoxy-5-chloro-2-                                                                       8   3  --  --   4    4    4   4                                   (trifluoromethyl)-1H-                                                          imidazo(4,5-b)pyri-                                                                         4   2  0   2    3    3    4   4                                   dine                                                                                        2   0    0.5                                                                              --   3      3.5                                                                                 3.5                                                                              4                                   __________________________________________________________________________      NOTE:                                                                          Dashes indicate species which were not tested.                           

EXAMPLES 71-76

Representative compounds of the present invention were evaluated for postemergent application to plants including corn and several weed species. The evaluation was carried out in accordance with the procedures of Examples 62-70 except that the test solutions were applied about 9-12 days after the preparation and seeding of the flats. The results are as set forth in the following table:

                                      TABLE II                                     __________________________________________________________________________     Injury Rating on Postemergent Treatment                                                       Lbs./  Crab-                                                                              Pig-                                                                              Fox-                                                                              Velvet-                                        Compound       Acre                                                                               Corn                                                                              grass                                                                              weed                                                                              tail                                                                              leaf                                           __________________________________________________________________________     1-Acetoxy-6-chloro-2-(tri-                                                                    8   4  4   4  4  4                                              fluoromethyl)-1H-imidazo-                                                      (4,5-b)pyridine                                                                               4   4  4   4  4  4                                                             2   4  4   4  4  4                                                             1   2  4   4  4  4                                              1-Ethoxy-6-chloro-2-(tri-                                                                     3   4  4   4  4  4                                              fluoromethyl)-1H-imidazo-                                                      (4,5-b)pyridine                                                                               4   4  4   4  4  4                                                             2   2  4   4  4  4                                                             1   1  4   4  3  4                                              1-(3,6-Dichloro-2-methoxy-                                                                    8   1  4   4  3  3                                              benzoyloxy)-6-chloro-2-(tri-                                                   fluoromethyl)-1H-imidazo-                                                                     4   0  3   2  3  3                                              (4,5-b)pyridine                                                                1-(Methylcarbamoyloxy)-6-                                                                     8   2  4   4  4  4                                              chloro-2-(trifluoromethyl)-                                                    1H-imidazo(4,5-b)pyridine                                                                     4   2  4   4  4  3                                                             2   2  4   4  3  4                                                             1   1  3.5 4  4  2.5                                                           1/2 0  4   3  4  2                                                             1/4 0  4   3  3  2                                              1-Methoxy-6-amino-5,7-dibromo-                                                                8   0  3   4  3  2                                              2-(trifluoromethyl)-1H-imidazo-                                                (4,5-b)-pyridine                                                               1-(Methylcarbamoyloxy)-6-                                                                     8   3  4   4  4  4                                              chloro-5,7-dibromo-2-(tri-                                                     fluoromethyl)-1H-imidazo-                                                      (4,5-b)pyridine                                                                __________________________________________________________________________

Essentially the same results as those reported in foregoing Examples 62-76 are obtained when evaluating the other representative compounds of Examples 1-61 hereinabove.

EXAMPLES 77-87

Other studies were carried out, evaluating various compounds of the present invention for preemergent application. These studies were made with a greater variety of plant species, at lower rates of application. Formulation of the compounds, however, was carried out in the same manner as described in preceding examples.

Rating of the herbicidal effect was on a scale of 0-10, with 0 indicating no herbicidal effect, and 10 indicating non-emergence or death. In addition, the kind of herbicidal effect was observed and recorded in accordance with the following notation system:

A = abscission of leaves

B = burned

C = chlorosis

D = death

E = epinasty

F = formative effects other than epinasty

G = dark Green

I = increased plant growth

L = local necrosis

N = no germination

P = purple pigmentation

R = reduced germination

S = stunting

U = unclassified injury

                                      TABLE III                                    __________________________________________________________________________                                            Morn-    Vel-                                                                              Fox-   Barn-                              Lbs./  Cot-                                                                              Soy-  Pea-  Soy-                                                                              ing-                                                                               Cockle-                                                                             vet-                                                                              tail                                                                               Rag-                                                                              yard                 Compound      Acre                                                                               Corn                                                                              ton                                                                               bean                                                                              Rice                                                                              nut                                                                               Corn                                                                              bean                                                                              glory                                                                              bur  leaf                                                                              Millet                                                                             weed                                                                              Grass                __________________________________________________________________________     1-Methoxy-6-chloro-2-                                                                        0.5 2SC                                                                               0  0  0  0  0  0  10D 4BC  3BC                                                                               5BC 8BC                                                                               8BC                  (trifluoromethyl)-1H-                                                          imidazo(4,5-b)pyridine                                                                       1.0 4SC                                                                               3B 5BC                                                                               4BC                                                                               0  2SC                                                                               3CB                                                                               10D 10D  7BC                                                                               9BC 10D                                                                               9BC                                2.0 5SC                                                                               7BC                                                                               9BC                                                                               6BC                                                                               3C 4SC                                                                               8CB                                                                               10D 10D  10D                                                                               10D 10D                                                                               9.5BC                1-Acetoxy-6-chloro-2-                                                                        0.5 0  0  0  0  0  0  0  10D   -- 4BC                                                                               4BC 8BC                                                                               2BC                  (trifluoromethyl)-1H-                                                          imidazo(4,5-b)pyridine                                                                       1.0 4SC                                                                               6BC                                                                               5BC                                                                               4BC                                                                               0  3SC                                                                               6BC                                                                               10D 10D  8BC                                                                               5BC 10D                                                                               4BC                                2.0 5SC                                                                               10D                                                                               10D                                                                               7BC                                                                               3C 6SC                                                                               9BC                                                                               10D 10D  9BC                                                                               9.5BC                                                                              10D                                                                               8.5BC                1-Ethoxy-6-chloro-2-                                                                         0.5 0  0  0  0  0  0  0  2BC 0    0  0   8BC                                                                               0                    (trifluoromethyl)-1H-                                                          imidazo(4,5-b)pyridine                                                                       1.0 0  0  0  0  0  0  0  10D 0    7BC                                                                               8BC 10D                                                                               8BC                                2.0 2SC                                                                               0  6BC                                                                               5BC                                                                               0  3SC                                                                               9BC                                                                               10D 10D  9BC                                                                               10D 10D                                                                               9BC                  1-Benzyloxy-6-chloro-2-                                                                      0.5 0  0  0  0  0  0  0  0   0    0  0   4BC                                                                               0                    (trifluoromethyl)-1H-                                                          imidazo(4,5-b)pyridine                                                                       1.0 0  0  0  0  0  0  0  2SC   -- -- 5SC 3BC                                                                               4BC                                2.0 0  0  0  0  0  0  0  5BC 0    3SC                                                                               3SB 3BC                                                                               4BC                  1-Allyloxy-6-chloro-2-                                                                       0.5 0  0  0  0  0  0  0  9BC 0    4BC                                                                               0   6BC                                                                               3BC                  (trifluoromethyl)-1H-                                                          imidazo(4,5-b)pyridine                                                                       1.0 0  0  0  0  0  0  0  10D 0    8BC                                                                               7BC 9BC                                                                               8BC                                2.0 0  0  0  3BC                                                                               0  0  4BC                                                                               10D 5BC  8.5                                                                               9.5BC                                                                              9BC                                                                               9BC                                                                  BC                             1-Isopropoxy-6-chloro-2-                                                                     0.5 0  0  0  0  0  0  0  8BC 2C   2BC                                                                               0   6BC                                                                               0                    (trifluoromethyl)-1H-                                                          imidazo(4,5-b)pyridine                                                                       1.0 0  0  0  0  0  0  0  10D 2C   2BC                                                                               2S  9BC                                                                               4BC                                2.0 2SC                                                                               0  0  0  0  0  0  10D   -- 6BC                                                                               8.5BC                                                                              9.5                                                                               9BC                                                                         BC                      1-(Allylcarbamoyloxy-                                                                        0.5 0  0  0  0  0  0  0  8BC 4BC  0  2S  6BC                                                                               0                    6-chloro-2-(trifluoro-                                                         methyl)-1H-imidazo-                                                                          1.0 0  0  0  2BC                                                                               0  0  0  10D 10D  2BC                                                                               4BC 8BC                                                                               6BC                  (4,5-b)pyridine                                                                              2.0 0  5BC                                                                               5BC                                                                               6BC                                                                               2C 2SC                                                                               5BC                                                                               10D 10D  5BC                                                                               8BC 10D                                                                               8BC                  1-Octanoyloxy-6-chloro-                                                                      0.5 0  0  0  0  0  0  0  7BC   -- 0  0   5BC                                                                               0                    2-(trifluoromethyl)-1H-                                                        imidazo(4,5-b)pyridine                                                                       1.0 0  3C 5BC                                                                               3SB                                                                               0  0  2C 10D   -- 4BC                                                                               4BS 9BC                                                                               6BC                                2.0 3SC                                                                               7BC                                                                               7BC                                                                               5BC                                                                               0  4SC                                                                               7BC                                                                               10D 10D  9BC                                                                               8BC 9.5BC                                                                             7BC                  1-(2-Methoxy-3,6-dichloro-                                                                   0.5 0  3F 7F 6F 6F 0  8F 7F  10D  2F 2S  8F 5FS                  benzoyloxy)-6-chloro-2-                                                        (trifluoromethyl)-1H-                                                                        1.0 2S 5F 10D                                                                               8F 10D                                                                               0  10D                                                                               8F    -- 8F 3SF 10D                                                                               4FS                  imidazo(4,5-b)pyridine                                                                       2.0 4S 9F 10D                                                                               9F 9F 1S 10D                                                                               10D 10D  10D                                                                               4SF 10D                                                                               5FS                  1-(Methylcarbamoyloxy)-6-                                                                    0.5 0  0  0  0  0  0  0  10D   -- 4BC                                                                               2BC 9BC                                                                               5BC                  chloro-2-(trifluoro-                                                           methyl)-1H-imidazo-                                                                          1.0 2SC                                                                               3SC                                                                               4BC                                                                               4BC                                                                               0  1SC                                                                               3BC                                                                               10D 10D  7BC                                                                               8BC 10D                                                                               4BC                  (4,5-b)pyridine                                                                              2.0 4SC                                                                               8BC                                                                               10D                                                                               6BC                                                                               0  5SC                                                                               10D                                                                               10D 10D  10D                                                                               10D 10D                                                                               10D                  1-Ethoxy-2,6-bis(trifluoro-                                                                  0.5 0  0  0  0  0  0  0  7BC    --                                                                               0  0   0  0                    methyl)-1H-imidazo(4,5-b)-                                                     pyridine      1.0 0  0  0  0  0  0  0  10D   -- 2BC                                                                               0   7BC                                                                               2S                                 2.0 3SC                                                                               2SC                                                                               4BC                                                                               2BC                                                                               0  5SC                                                                               8BC                                                                               10D 10D  4BC                                                                               9BC 9BC                                                                               3S                   Control           0  0  0  0  0  0  0  0   0    0  0   0  0                    Control           0  0  0  0  0  0  0  0   0    0  0   0  0                    __________________________________________________________________________

EXAMPLE 88

1-Methoxy-6-chloro-2-(trifluoromethyl)-1H-imidazo-(4,5-b)pyridine was evaluated under field conditions. The compound was formulated in conventional procedures and applied as a soil surface spray to beds seeded with corn and selected weed species. The evaluations were carried out in a sub-tropical climate; there having been no rainfall in the first seven days following application, 1/2 inch of sprinkler irrigation was applied. Observations were made periodically for emergence, corn injury, and weed control. The results were as expressed in the following table, with date of observation expressed as the number of days from the day of seeding and compound application.

                                      TABLE IV                                     __________________________________________________________________________                                       Percent weed Control--                                                         All Observations Day 17                                 Rate                                                                               Emergence.sup.a                                                                          Crop Injury.sup.c              Black                             (Lbs./                                                                             Day Day                                                                               Day                                                                               Day                                                                               Day                                                                               Day                                                                               Prickly                                                                            Venice                                                                             Common                                                                              Morning                                                                              Foxtail                                                                           night-                                                                             Pig                Compound   Acre                                                                               5   7  11 11 17 38 sida                                                                               mallow                                                                             purslane                                                                            glory millet                                                                            shade                                                                              weed               __________________________________________________________________________     1-methoxy-6-chloro-2-                                                                     1   97  90 89 0.0                                                                               0.0                                                                               0.0                                                                               98  90  100  89   98  100 100                (trifluoromethyl)-1H-                                                          imidazo(4,5-b)pyridine                                                                    1.5 97  89 87 0.0                                                                               0.3                                                                               0.0                                                                               99  97  100  100  99  100 100                           2   72  94 95 0.0                                                                               0.7                                                                               0.0                                                                               99  96  100  91   99  100 100                           3    100+                                                                              100                                                                               98 0.3                                                                               2.3                                                                               1.7                                                                               100 100 100  96   100 100 100                           4   96  85 83 2.0                                                                               3.7                                                                               4.3                                                                               100 100 100  100  100 100 100                Control    0   100 100                                                                               100                                                                               0.0                                                                               0.0                                                                               0.0                                                                               0   0   0    0    0   0   0                                 (72).sup.b                                                                         (108)                                                                             (109)       (14.6).sup.d                                                                       (5.6)                                                                              (3.8)                                                                               (5)  (24.5)                                                                             (2.6)                                                                              (4.1)              __________________________________________________________________________      .sup.a Emergence expressed as a percent of the control.                        .sup.b Number of emerged corn seedings per 15 feet of row.                     .sup.c Crop injury on a 0-10 scale where 0 = no injury, 1-3 = slight, 4-6      = moderate, 7-9 = severe, and 10 = death of all plants.                        .sup.d Weeds/sq.ft. based on 5 one sq. ft. counts per plot.              

as noted above, the compounds of the present invention can be used in conjunction with other agricultural materials, including other herbicides. Thus, in one embodiment, the present invention is directed to a method which comprises applying essentially simultaneously to a plant part an amount of a first substance which is:

1-methoxy-6-chloro-2-trifluoromethyl-1H-imidazo(4,5-b)-pyridine,

1-methoxy-5-chloro-2-trifluoromethyl-1H-imidazo(4,5-b)-pyridine, or

1-methoxy-2,6-bis(trifluoromethyl)-1H-imidazo(4,5-b)-pyridine;

and an amount of a second substance which is:

alachlor,

atrazine,

butylate,

2-chloro-4-(1-cyano-1-methylethylamino)-6-ethylamino-s-triazine,

dalapon,

dinoseb,

diuron,

EPTC,

linuron,

oryzalin,

propachlor,

propazine,

simazine,

trifluralin, or

TCA,

the amounts being such as to effect, in combination, growth inhibition. This embodiment of the present invention also comprehends a combination of the first and second substances, which combination is useful in implementing the method.

The substances serving as the second substance of the present herbicidal methods and combinations are in every instance known compounds. For a convenient compilation of information and references on these and other known herbicides, attention is directed to the Herbicide Handbook of the Weed Society of America, sec. ed., published by The W. F. Humphrey Press, Inc., Geneva, New York, 1970, and available from Weed Science Society of America, Department of Agronomy, University of Illinois, Urbana, Illinois 61801.

The known herbicides serving as the second substance are generally crystalline solids, typically white in color; the exceptions are butylate (an amber liquid); EPTC (a light yellow-colored liquid); and dinoseb (which may exist as either a dark brown solid or a dark orange liquid, depending on temperature). Each of these compounds is individually effective at a range of rates, depending upon the particular substance, the particular use (for example, whether a selective or general herbicidal effect is sought), and the type of soil and other growing conditions. The generally established rate ranges for these known herbicides, when used individually, are as follows:

    ______________________________________                                                              Established Rate                                          Compound             in Lbs./Acre                                              alachlor             1-4                                                       atrazine             2-4                                                       butylate             3-4                                                       2-chloro-4-(1-cyano-1-methyl-                                                  ethylamino)-6-ethylamino-                                                      s-triazine           1-4                                                       dalapon              .75-20                                                    dinoseb              .75-12                                                    diuron               0.6-6.4 (selective)                                                            4-16 (general)                                            EPTC                 2-6                                                       linuron              0.5-3 (selective)                                                              1-3 (non crop)                                            oryzalin             1-4                                                       propachlor           3-6                                                       propazine            1-4                                                       simazine             2-4                                                       trifluralin          0.5-2                                                     TCA                  4--30 (selective)                                                              50-200 (general)                                          ______________________________________                                          (Herbicide Handbook of the Weed Society of America, supra).              

In employing these known herbicides in combination with the herbicides of the present invention, the precise ratio of the herbicidal agents to one another is not critical. It is generally preferred that the known herbicide be used in an amount within its established rate range for individual use as sole herbicidal agent, although because of the herbicidal effect attributable to the ether, lesser amounts within the established rate range or amounts below the established rate range are appropriate. Thus, amounts below the median of the established rate range generally give good results in combination with the specified ethers. However, each of the ether and known herbicide components should be employed in an amount which, if employed individually as sole herbicidal agent, would exert at least a minimal plant-growth inhibiting effect. In the case of alachlor, atrazine, and propachlor, for example, the established rate ranges are 1-4 lbs./acre of alachlor, 2-4 lbs./acre of atrazine, or 3-6 lbs./acre of propachlor; but good results generally are obtained in the present combinations at application rates of 2.5 lbs./acre or less of alachlor, 3 lbs./acre or less of atrazine, or 4.5 lbs./acre or less of propachlor. For the specified ethers serving as the first component, application rates of 0.25-4 lbs./acre are desirable for selective activity, and preferred rates for selective activity are generally 1-2.5 lbs./acre.

The substances can be administered separately, although preferably essentially simultaneously, and this mode of administration is sometimes preferred. Thus, for example, different herbicides may require different modes of applications which preclude a single application. In particular, each of butylate and EPTC is preferably applied to corn prior to planting and with mechanical mixing into the soil. The ethers of the present invention are preferably applied to corn immediately after seeding but without mechanical mixing. Thus, separate administration is sometimes preferred in order to make best utilization of the respective herbicidal properties. Where separate administration is preferred, the exact interval between applications is not critical; but optimal results generally are obtained when the respective administrations are essentially simultaneously, such as within several minutes to not more than within several hours of one another. The time interval between applications is largely dictated by the practicalities of agricultural practices.

Generally, however, it is preferred that both substances be formulated as a single formulation. The formulation is conducted in accordance with conventional procedures, utilizing such adjuvants as surface-active agents, inert finely-divided solids, and the like. Reference is made to the discussion hereinabove concerning formulation of the compounds of the present invention, generally. Where the objective is selective herbicidal activity, it is generally preferred that the specified ether comprise at least 40 percent by weight of the total herbicidally-active component.

EXAMPLES 89-103

1-Methoxy-6-chloro-2-trifluoromethyl-1H-imidazo(4,5-b)pyridine was evaluated in combination with each of a number of known herbicides. The evaluation was conducted in each case in accordance with the standard screening procedures described in preceding examples, each of the herbicides being applied separately but within rapid succession (within an interval of not longer than about 5 minutes).

The results observed were as set forth in the following tables.

                                      TABLE V                                      __________________________________________________________________________     COMBINATION OF 1-METHOXY-6-CHLORO-2-TRIFLUOROMETHYL-                           1H-IMIDAZO(4,5-b)PYRIDINE ("A") WITH ALACHLOR ("B")                                Rates                                                                               Morn-          Barn-                                                                              Large                      John-                                                                              Lambs               Com-                                                                               Lbs./                                                                               ing    Foxtail                                                                            Rag-                                                                               yard                                                                               Crab-                                                                              Pig-                                                                               Sor-    Velvet Jimson                                                                             son Quar-               pounds                                                                             Acre Glory                                                                              Corn                                                                              Millet                                                                             weed                                                                               Grass                                                                              grass                                                                              weed                                                                               ghum                                                                               Rice                                                                               Leaf                                                                               Corn                                                                              Weed                                                                               Grass                                                                              ter                 __________________________________________________________________________     A+B  0.25+0.5                                                                           10D 0  10D 9SB 10N 9.5RS                                                                              9.5RS                                                                              3SB 9SR 4SB 0  6SB 9SB 9S                  "   0.25+1                                                                              1OD 0  1OD 9SR 1ON 9.9SR                                                                              1ON 5SB 1ON 7SB 0  1OD 1OD 1ON                 "   0.25+2                                                                              1OD 1S 1OD 9.5RS                                                                              1ON 1ON 1ON 9SF 1ON 9SB 0  9BS 1OD 1ON                 "   0.25+4                                                                              1OD 2S 1ON 1OD 1ON 1ON 1ON 8SF 1ON 9BS 2S 9BS 1OD 1ON                 "   0.5+0.5                                                                             1OD 0  1OD 1OD 1ON 9.5RS                                                                              9.5RS                                                                              3SB 8S  8SB 1S 8BS 9BS 1ON                 "   0.5+1                                                                               1OD 0  1ON 1OD 1ON 1OD 9.5RS                                                                              4BSF                                                                               8RS 8BSR                                                                               0  9.5BS                                                                              1ON                     "   0.5+2                                                                               1OD 3S 1OD 9.5BSR                                                                             1ON 1ON 1OD 8SF 1ON 9BS 0  9BS 9.5BS                                                                              9RS                 "   0.5+4                                                                               1OD 3S 1ON 1ON 1ON 1ON 1ON 9FSR                                                                               9.8RS                                                                              9.5BS                                                                              2S 9.5BS                                                                              1ON 1ON                 "     1+0.5                                                                             1OD 2SB                                                                               1OD 1OD 1ON 9.5BS                                                                              9.5RS                                                                              7BS 8BSR                                                                               9BS 0  9BS 7BS 9RS                 "   1+1  1OD 1S 1OD 10D 1ON 9.8RS                                                                              9.8RS                                                                              8BS 9RS 1OD 3S 9BS 10D 1ON                 "   1+2  1OD 3S 1ON 9.8RSB                                                                             1ON 9.8RS                                                                              1ON 8BSF                                                                               9.5RS                                                                              1OD 0  9.5BS                                                                              1OD 1ON                 "   1+4  1OD 3S 1OD 9.5BSR                                                                             1ON 1OD 1ON 9BSF                                                                               9.5RS                                                                              9SB 2S 9.5BS                                                                              1OD 1ON                 "     2+0.5                                                                             1OD 3S 1OD 8S  1ON 9.8RS                                                                              9.5RS                                                                              9.5BS                                                                              7SB 1OD 3S 9.5BS                                                                              9BS 9.8RS               "   2+1  1OD 1S 1OD 9.5RS                                                                              1ON 1ON 9.8RS                                                                              9   9RS 8BS 1S 9.8BS                                                                              9BS 1ON                 A+B 2+2  1OD 0  1OD 9.8RS                                                                              1ON 1ON 1ON 9BS 1OD 9.5BS                                                                              1SB                                                                               9.5BS                                                                              1OD 1ON                 "   2+4  1OD 3S 1OD 1OD 1ON 1ON 1ON 9.5BSF                                                                             1ON 9.5BS                                                                              4SB                                                                               9.8BS                                                                              1OD 1ON                 Con-                                                                               0    0   0  0   0   0   0   0   0   0   0   0  0   0   0                   trol                                                                           __________________________________________________________________________

                                      TABLE VI:                                    __________________________________________________________________________     COMBINATION F 1-METHOXY-6-CHLORO-2-TRIFLUOROMETHYL-1H-                         IMIDAZO(4,5-b)PYRIDINE ("A") WITH ATRAZINE ("B")                                                                                  Fox-                              Rates                                                                              Morn-          Vel-                                                                               Lambs   Barn-  Large  tail    John-                     Lbs./                                                                              ing Pig-                                                                               Rag-   vet Quar-                                                                              JImson                                                                             yard   Crab-  mil-                                                                               Sor-                                                                               son                 Compounds                                                                            Acre                                                                               Glory                                                                              weed                                                                               weed                                                                               Corn                                                                              Leaf                                                                               ter Weed                                                                               Grass                                                                              Rice                                                                              grass                                                                              Corn                                                                              let ghum                                                                               Grass               __________________________________________________________________________     A + B 1/4 1/4                                                                            8SD 9RS 8RS                                                                               0   3BS 7RS 8.5SD                                                                              5BS 2BS                                                                               4S  0  3S  0   2S                  "     1/4 1/2                                                                            1OD 9.5RS                                                                              8RDS                                                                              0   5BS 7RSD                                                                               9SD 8SD 3BS                                                                               4S  0  4BS 0   2S                  "     1/4 1                                                                              9.5SD                                                                              1ON 8RDS                                                                              0   7SD 7RS 9SD 9.5SD                                                                              3BS                                                                               6S  0  4BS 0   4BS                 "     1/4 2                                                                              1OD 9.5RS                                                                              9.5RDS                                                                            0   9.5SD                                                                              7RS 9.5SD                                                                              9.5SD                                                                              3BS                                                                               8S  0  7SD 0   4BS                 "     1/2 1/4                                                                            1OD 9.5RS                                                                              6.5SD                                                                             0   7SD 7.5RS                                                                              9SD 9SD 3BS                                                                               7RS 0  8SD 0   4BS                 "     1/2 1/2                                                                            1OD 9RS 9SD                                                                               0   7SD 5RS 9.5SD                                                                              9.5SD                                                                              4BS                                                                               7RS 0  7SD 0   7SD                 "     1/2 1                                                                              1OD 9.5RS                                                                              9.5RSD                                                                            1S  6SD 6.5RS                                                                              9SD 9SD 3BS                                                                               8SD 0  8.5SD                                                                              0   6.5SD               "     1/2 2                                                                              1OD 9RS 9.5RSD                                                                            0   9SD 7RS 8.5SD                                                                              1OD 3BS                                                                               9SD 0  9.5SD                                                                              0   6.5SD               "     1 1/4                                                                              1OD 9RS 9SD                                                                               0   6.5SD                                                                              7RS 9SD 9.5SD                                                                              3BS                                                                               9.5SD                                                                              0  1OD 3BS 7SD                 "     1 1/2                                                                              1OD 9.5RS                                                                              9.5SD                                                                             0   9SD 7RS 9.5SD                                                                              9.5SD                                                                              2BS                                                                               9.5SD                                                                              0  1OD 4BS 8SD                 "     1 1 1OD 9.5RS                                                                              1OD                                                                               0   9SD 8RS 9.5SD                                                                              1OD 3BS                                                                               9.5SD                                                                              0  1OD 4BS 7SD                 "     1 2 1OD 9.5RS                                                                              1OD                                                                               0   9SD 7RSD                                                                               9.5SD                                                                              1OD 3BS                                                                               9.5SD                                                                              0  1OD 3BS 9SD                 "     2 1/4                                                                              1OD 9.5RS                                                                              9SD                                                                               1S  9.5SD                                                                              7RS 9.5SD                                                                              1OD 3BS                                                                               9.5SD                                                                              0  1OD 7SD 9.5SD               "     2 1/2                                                                              1OD 9.5RS                                                                              1OD                                                                               0   9.5SD                                                                              7.5RS                                                                              9.5SD                                                                              9.5SD                                                                              4BS                                                                               1OD 0  1OD 8SD 9SD                 "     2 1 1OD 9.5RS                                                                              1OD                                                                               2S  1OD 8RS 9.5SD                                                                              9.5SD                                                                              5BS                                                                               9.5SD                                                                              1S 1OD 8SD 9SD                 "     2 2 1OD 9.5RS                                                                              1OD                                                                               2S  1OD 8RS 1OD 1OD 4BS                                                                               9.5SD                                                                              0  1OD 7SD 9SD                 Control                                                                              -- --                                                                              0   0   0  0   0   0   0   0   0  0   0  0   0   0                   Control                                                                              -- --                                                                              0   0   0  0   0   0   0   0   0  0   0  0   0   0                   Control                                                                              -- --                                                                              0   0   0  0   0   0   0   0   0  0   0  0   0   0                   __________________________________________________________________________

                                      TABLE VII                                    __________________________________________________________________________     COMBINATION OF 1-METHOXY-6-CHLORO-2-TRIFLUOROMETHYL-                           1H-IMIDAZO(4,5-b)PYRIDINE ("A") WITH BUTYLATE ("B")                                  Rates Mor-   Fox-   Barn-                                                                              Large        Vel-                                      Lbs./ ning   tail                                                                               Rag-                                                                              yard                                                                               Crab-                                                                              PIg-                                                                              Sor-  vet   Jimson                                                                             Johnson                                                                             Lambs                Compounds                                                                            Acre  Glory                                                                              Corn                                                                              Millet                                                                             weed                                                                              Grass                                                                              grass                                                                              weed                                                                              ghum                                                                              Rice                                                                              Leaf                                                                              Corn                                                                              Weed                                                                               Grass                                                                               Quarter              __________________________________________________________________________     A + B 0.25 + 1.0                                                                           1OD 0  7SF 5SB                                                                               3S  4SB 9.5BS                                                                             9SF                                                                               0  1OD                                                                               0  4SB 9SR  1OD                  "     0.25 + 2.0                                                                           6SB 0  9SF 6SB                                                                               8S  6SB 9BS                                                                               1OD                                                                               3S 1OD                                                                               0  6SB 9.5RS                                                                               1OD                  "     0.25 + 3.0                                                                           1OD 0  9SBF                                                                               4SB                                                                               8SB 1OD 9BSR                                                                              1OD                                                                               7S 1OD                                                                               0  7SB 1OD  1OD                  "     0.25 + 4.0                                                                           1OD 0  9SB 8SB                                                                               8SB 1OD 1OD                                                                               1OD                                                                               9SB                                                                               1OD                                                                               0  7SB 1OD  1OD                  41    0.5 + 1.0                                                                            1OD 1S 6SB 9.5                                                                               7SB 5SB 8BS                                                                               3S 1OD                                                                               2S 9BS                                                                               9RSB                                                                               10D                                          BS             SBF                                          "     0.5 + 2.0                                                                            9BS 1S 8BS 1OD                                                                               8SB 9.5RS                                                                              1OD                                                                               10D                                                                               6S 1OD                                                                               1S 8BS 9RS  1OD                  "     0.5 + 3.0                                                                            1OD 3S 9.5BS                                                                              9.5                                                                               1OD 1OD 1OD                                                                               1OD                                                                               9.5S                                                                              1OD                                                                               1S 9BS 1OD  10D                                         RS                                                      "     0.5 + 4.0                                                                            1OD 4S 9.5 9.5                                                                               1OD 1OD 1OD                                                                               1OD                                                                               9.5S                                                                              10D                                                                               3S 9BS 1OD  10D                                     BSR BSR                                                     "     1.0 + 1.0                                                                            1OD 5S 1OD                                                                            1OD 9.5BS                                                                             9BS 9.5 9.5                                                                               3B 1OD                                                                               4S 9BS                                                                               9BS 10D                                                         BS BS                                        "     1.0 + 2.0                                                                            1OD 5S 1OD 1OD                                                                               9.5BS                                                                              1OD 1OD                                                                               1OD                                                                               8S 1OD                                                                               4S 9BS 1OD  1OD                  "     1.0 + 3.0                                                                            1OD 4S 1OD 1OD                                                                               8BS 8BS 9BS                                                                               1OD                                                                               5S 1OD                                                                               3S 7BS 9.5BS                                                                               10D                  "     1.0 + 4.0                                                                            10D 3S 10D 10d                                                                               9.5 9.5BS                                                                              9.5                                                                               9SF                                                                               7S 10D                                                                               3S 9BS 10D  10D                                            BSR     FS                                           "     2.0 + 1.0                                                                            10D 5S 10D 10D                                                                               9.5BS                                                                              9BS 9BS                                                                               8  3B 10D                                                                               5SB                                                                               8SB 9BS  10D                                                       BSF                                       "     2.0 + 2.0                                                                            10D 5S 10D 10D                                                                               9.5BS                                                                              10D 8S 9.5                                                                               5S 10D                                                                               6SB                                                                               8BS 9BSR 9SB                                                          BSF                                    A + B 2.0 + 3.0                                                                            10D 6SB                                                                               10D 10D                                                                               10D 9.5BS                                                                              9.5                                                                               10D                                                                               8S 10D                                                                               5S 8BS 9.5RS                                                                               10D                                                    SB                                           "     2.0 + 4.0                                                                            10D 6SB                                                                               10D 10D                                                                               10D 10D 9.5                                                                               10D                                                                               9S 10D                                                                               6SB                                                                               9BS 10D  10D                                                    BS                                           Control                                                                              0     0   0  0   0  0   0   0  0   0 0  0  0   0    0                    __________________________________________________________________________

                                      TABLE VIII                                   __________________________________________________________________________     COMBINATION OF 1-METHOXY-6-CHLORO-2-TRIFLUOROMETHYL-1H-                        IMIDAZO(4,5-b) PYRIDINE ("A") WITH 2-CHLORO-4-(1-CYANO=                        1-METHYLETHYLAMINO)-6-ETHYLAMINO-s-TRIAZINE ("B")                                    Rates Mor-   Fox-   Barn-                                                                              Large        Vel-                                      Lbs./ ning   tail                                                                               Rag-                                                                              yard                                                                               Crab-                                                                              Pig-                                                                              Sor-  vet   Jimson                                                                             Johnson                                                                             Lambs                Compounds                                                                            Acre  Glory                                                                              Corn                                                                              Millet                                                                             weed                                                                              Grass                                                                              grass                                                                              weed                                                                              ghum                                                                              Rice                                                                              Leaf                                                                              Corn                                                                              Weed                                                                               Grass                                                                               Quarter              __________________________________________________________________________     A + B 0.25 + 0.25                                                                          10D 0  10D 10D                                                                               4SB 6SB 5S 3SB                                                                               4S 9BS                                                                               2S 9BS 7BS  8SB                  "     0.25 + 0.5                                                                           10D 3S 10D 10D. 7SB                                                                          9.5BS                                                                              7S  8BS                                                                               9BS                                                                               9.5                                                                               2S 9.5BS                                                                             9.5BS                                                                              8SB                                                                  BS                                  "     0.25 + 1.0                                                                           10D 4S 10D 10D                                                                               9.5BS                                                                              10D 7SB                                                                               6SB                                                                               8BS                                                                               10D                                                                               3S 10D 10D  9.5BS                "     0.25 + 2.0                                                                           10D 5S 10D 10D                                                                               10D 10D 10D                                                                               9.5                                                                               10D                                                                               10D                                                                               4SB                                                                               9.5BS                                                                              9.5BS                                                                               9.5BS                                                     BS                                        "     0.5 + 0.25                                                                           10D 3S 10D 10D                                                                               8SB 7SB 6SB                                                                               6SB                                                                               8B 9BS                                                                               3S 9BS 9.5BS                                                                               8S                   "     0.5 + 0.5                                                                            10D 2S 10D 10D                                                                               8SB 9.5SB                                                                              6SB                                                                               6SB                                                                               8B 10D                                                                               2S 9BS 9.5BS                                                                               9SB                  "     0.5 + 1.0                                                                            10D 2SB                                                                               10D 10D                                                                               9.5SB                                                                              10D 9.5                                                                               9.5                                                                               10D                                                                               9.8                                                                               2SB                                                                               9.5BS                                                                              9BS  9SB                                                    BS BS    BS                                  "     0.5 + 2.0                                                                            10D 3SB                                                                               10D 10D                                                                               9.5BS                                                                              10D 9.5                                                                               9.8                                                                               10D                                                                               10D                                                                               2S 9.5BS                                                                              10D  9.58SB                                                 BS BS                                        "     1.0 + 0.25                                                                           9.5BS                                                                              2S 10D 10D                                                                               9.5BS                                                                              10D 8SB                                                                               7SB                                                                               7B 9.5BS                                                                             2S 9.5BS                                                                              9.5BS                                                                               9SB                  "     1.0 + 0.5                                                                            10D 2SB                                                                               10D 10D                                                                               9.5BS                                                                              10D 9.5                                                                               9.5                                                                               10D                                                                               10D                                                                               2S 9.5SB                                                                              10D  9S                                                     BS BS                                        "     1.0 + 1.0                                                                            10D 2SB                                                                               10D 10D                                                                               9.5BS                                                                              9.8BS                                                                              9.5                                                                               9.5                                                                               10D                                                                               10D                                                                               2S 10D 9.5BS                                                                               9.5SB                                                  SB BS                                        "     1.0 + 2.0                                                                            10D 4SB                                                                               10D 10D                                                                               9.5BS                                                                              10D 9.5                                                                               10D                                                                               10D                                                                               9.8                                                                               3S 9.5BS.                                                                             9SB                                                         BS       BS                                  "     2.0 + 0.25                                                                           10D 2S 10D 10D                                                                               9.5BS                                                                              9.5BS                                                                              9.5                                                                               8SB                                                                               7BS                                                                               9.5                                                                               3S 9.5BS                                                                              9.5BS                                                                               9SB                                                    BS SB    BS                                  "     2.0 + 0.5                                                                            10D 5SB                                                                               10D 10D                                                                               10D 10D 9.5                                                                               9.5                                                                               10D                                                                               10D                                                                               5SB                                                                               9.5BS                                                                              10D  10D                                                    BS BS                                        "     2.0 + 1.0                                                                            10D 4SB                                                                               10D 10D                                                                               10D 10D 9.8                                                                               10D                                                                               10D                                                                               10D                                                                               3SB                                                                               10D 10D  9SB                                                    BS                                           "     2.0 + 2.0                                                                            10D 4SB                                                                               10D 10D                                                                               10D 10D 9.5                                                                               10D                                                                               10D                                                                               10D                                                                               5SB                                                                               10D 10D  10D                                                    BS                                           Control                                                                              0     0   0  0   0  0   0   0  0  0  0  0  0   0    0                    __________________________________________________________________________

                                      TABLE IX:                                    __________________________________________________________________________     COMBINATION OF 1-METHOXY-6-CHLORO-2-TRIFLUOROMETHYL-                           1H-IMIDAZO(4,5-b)PYRIDINE ("A") WITH DALAPON ("B")                                              Fox-                                                              Rates Morn-  tail    Barn-                                                                              Large          Vel-   Jim-                                                                               John-                                                                              Lambs               Com-                                                                               Lbs./ ing    Mil-                                                                               Rag-                                                                               yard                                                                               Crab-                                                                              Pig-                                                                               Sor-   vet    son son Quar-               Pounds                                                                             Acre  Glory                                                                              Corn                                                                              let weed                                                                               Grass                                                                              grass                                                                              weed                                                                               ghum                                                                               Rice                                                                              Leaf                                                                               Corn                                                                              Weed                                                                               Grass                                                                              ter                 __________________________________________________________________________     A + B                                                                              0.25 + 0.75                                                                          3SBC                                                                               0  4SB 3S  0   2S  4S  0   0  3SB 0  0   0   0                   "   0.25 + 1.5                                                                           2B  0  6BS 10D 0   0   4B  0   2S 3S  0  0   0   0                   "   0.25 +  3.0                                                                          2B  0  9BS 10D 0   7SB 3BS 0   6SB                                                                               4S  0  4B  0   3S                  "   0.25 + 6.0                                                                           3SB 0  10D 9BS 3BS 8BS 4BS 3BS 5SB                                                                               3SB 0  4BS 0   --                  "   0.5  + 0.75                                                                          6SB 0  8BSR                                                                               10D 2S  5SB 5SB 0   0  4S  0  7BS 3S  7SR                 "   0.5  + 1.5                                                                           9BS 0  9BS 1OD 4BS 8BS 3B  1S  3S 6SB 0  8BS 0   6RS                 "   0.5  + 3.0                                                                           9BS 1S 1OD 1OD 5SB 7SB 3B  1S  5SB                                                                               7SB 0  6BS 2S  7RS                 "   0.5  + 6.0                                                                           1OD 0  1OD 9.5BS                                                                              7BS 8BS 1OD 3SB 7BS                                                                               7SB 0  8BS 2S  7RS                 "   1.0 + 0.75                                                                           9.5BS                                                                              0  1OD 1OD 6BS 1OD 6BS 3SB 5BS                                                                               9.5BS                                                                              0  1OD 4S  6SR                 "   1.0  + 1.5                                                                           9.5BS                                                                              0  1OD 1OD 4SB 9BS 7BS 2SB 4B 1OD 0  1OD 3SB 7SR                 "   1.0  + 3.0                                                                           1OD 0  1OD 1OD 5BS 9.5BS                                                                              9BS 3SB 5BS                                                                               1OD 0  1OD 6BS 7RS                 "   1.0  + 6.0                                                                           1OD 4F 1OD 1OD 7BSR                                                                               1OD 1OD 6BSF                                                                               9BS                                                                               1OD 4FS                                                                               1OD 4SB 8S                  "   2.0 + 0.75                                                                           1OD 0  1OD 1OD 4BS 7BS 9BS 8BS 6BS                                                                               9.5BS                                                                              2S 1OD 8BS 1OD                 "   2.0  + 1.5                                                                           1OD 3S 1OD 1OD 9BS 1OD 9BS 8BS 9BS                                                                               1OD 3S 1OD 7BS 1OD                 "   2.0  + 3.0                                                                           1OD 1S 1OD 1OD 9BS 1OD 1OD 9BS 9BS                                                                               1OD 2S 1OD 7BS 9RS                 "   2.0  + 6.0                                                                           1OD 2S 1OD 1OD 9.5BS                                                                              1OD 1OD 6BS 8BS                                                                               1OD 4SB                                                                               9.5BS                                                                              8BS 9RS                 Con-                                                                           trol                                                                               0     0   0  0   0   0   0   0   0   0  0   0  0   0   0                   __________________________________________________________________________

                                      TABLE X:                                     __________________________________________________________________________     COMBINATION OF 1-METHOXY-6-CHLORO-2-TRIFLUOROMETHYL-                           1H-IMIDAZO(4,5-b)PYRIDINE ("A") WITH DINOSEB ("B")                                              Fox-                                                              Rates Morn-  tail    Barn-                                                                              Large          Vel-   Jim-                                                                               John-                                                                              Lambs               Com-                                                                               Lbs./ ing    Mil-                                                                               Rag-                                                                               yard                                                                               Crab-                                                                              Pig-                                                                               Sor-   vet    son son Quar-               pounds                                                                             Acre  Glory                                                                              Corn                                                                              let weed                                                                               Grass                                                                              grass                                                                              weed                                                                               ghum                                                                              Rice                                                                               Leaf                                                                              Corn                                                                               Weed                                                                               Grass                                                                              tert                __________________________________________________________________________     A + B                                                                              0.25 + 1.0                                                                           2B  0  0   7SB 0   2S  2S  0  0   3SB                                                                               0   7SB 2S  5S                  "   0.25 + 2.0                                                                           5SB 0  2S  1OD 0   0   2S  0  0   3SB                                                                               0   8BS 0   5S                  "   0.25 + 4.0                                                                           9BS 0  2S  1OD 2S  2S  6S  0  0   3S 0   9BS 0   5S                  "   0.25 + 8.0                                                                           9BS 0  4S  1OD 4SR 5RS 8SR 2S 3S  3S 1S  1OD 2S  6S                  "   0.5 + 6SB0                                                                               0  3SB 1OD 5SB 8BS 8SR 2S 3BS 5SB                                                                               0   9.5BS                                                                              2S  7S                  "   0.5 + 2.0                                                                            1OD 0  8BS 1OD 4SB 6SB 9SR 1SB                                                                               1B  5SB                                                                               0   9.5BS                                                                              3SB 9SR                 "   0.5 + 4.0                                                                            1OD 0  7SB 1OD 4SB 8BSR                                                                               7SR 2SB                                                                               2SB 6SB                                                                               0   9.5BS                                                                              2SB 7SR                 "   0.5 + 8.0                                                                            1OD 2S 7SB 1OD 7SR 7SRB                                                                               6SR 3S 2SB 5SB                                                                               0   1OD 2S  9SR                 "   1.0 + 1.0                                                                            1OD 2S 1OD 10D 9SB 9.5RS                                                                              1ON 7BS                                                                               1OD 1OD                                                                               1S  9.5BS                                                                              8BS 1OD                 "   1.0 + 2.0                                                                            1OD 1S 1OD 1OD 9BS 1OD 1OD 8BS                                                                               4BS 7BS                                                                               1S  1OD 6BS 1OD                 "   1.0 + 4.0                                                                            1OD 2SB                                                                               1OD 1OD 8BS 1OD 1OD 6BS                                                                               4BS 8BS                                                                               0   1OD 7BS 1OD                 "   1.0 + 8.0                                                                            1OD 1S 7BS 1OD 7BS 1OD 9.5RS                                                                              4BS                                                                               6SB 1OD                                                                               0   1OD 6BS 1OD                 "   2.0 + 1.0                                                                            1OD 4SB                                                                               1OD 1OD 1OD 1OD 9SB 9BS                                                                               8BS 1OD                                                                               4SB 1OD 1OD 1OD                 "   2.0 + 2.0                                                                            1OD 3S 1OD 1OD 1OD 1OD 1OD 1OD                                                                               8BS 1OD                                                                               4SB 1OD 9.5BS                                                                              1OD                 A + B                                                                              2.0 + 4.0                                                                            1OD 2S 1OD 1OD 9.5BS                                                                              1OD 1OD 9BS                                                                               8BS 1OD                                                                               1S  1OD 9.5BS                                                                              1OD                 "   2.0 + 8.0                                                                            1OD 3SB                                                                               1OD 1OD 1OD 10D 10D 8BS                                                                               8BSC                                                                               1OD                                                                               2S  1OD 1OD 1OD                 Con-                                                                           trol                                                                               0     0   0  0   0   0   0   0   0  0   0  0   0   0   0                   __________________________________________________________________________

                                      TABLE XI                                     __________________________________________________________________________     COMBINATION OF 1-METHOXY-6-CHLORO-2-TRIFLUOROMETHYL-                           1H-IMIDAZO(4,5-b)PYRIDINE ("A") WITH DIURON ("B")                                               Fox-                                                              Rates Morn-  tail   Barn-                                                                              Large          Vel-   Jim-                                                                               John-                                                                              Lambs                Com-                                                                               Lbs./ ing    Mil-                                                                              Rag-                                                                               yard                                                                               Crab-                                                                              Pig-                                                                               Sor-   vet    son son Quar-                pounds                                                                             Acre  Glory                                                                              Corn                                                                              let                                                                               weed                                                                               Grass                                                                              grass                                                                              weed                                                                               ghum                                                                               Rice                                                                              Leaf                                                                               Corn                                                                              Weed                                                                               Grass                                                                              ter                  __________________________________________________________________________     A + B                                                                              0.25 + 0.25                                                                          1OD 0  4SB                                                                               1OD 4BS 5SB 8BS 1B  1B 5BS 0  7BS 2SB 8SR                  "   0.25 + 0.5                                                                           6BSL                                                                               0  5BS                                                                               1OD 9BS 8BS 9BS 2B  4B 8BS 0  9BS 3BS 9SR                  "   0.25 + 1.0                                                                           1OD 0  8BS                                                                               1OD 1OD 9BS 9BS 3BC 3B 1OD 3S 9BS 8BS 9SR                  "   0.25 + 2.0                                                                           1OD 5BS                                                                               1OD                                                                               1OD 1OD 9.5BS                                                                              9BS 4BS 7B 1OD 5SB                                                                               9BS 9.5BS                                                                              1ON                  "   0.5 + 1OD25                                                                              2B 8BS                                                                               1OD 7BS 8BS 9.5RS                                                                              3SB 4B 9BS 0  9BS 7BS 9RS                  "   0.5 + 0.5                                                                            9BS 2SB                                                                               1OD                                                                               9.5BS                                                                              9BS 8BS 9BS 2S  4B 9BS 0  9BS 9.5BS                                                                              9.5RS                "   0.5 + 1.0                                                                            1OD 2S 1OD                                                                               1OD 1OD 9BS 9.5BS                                                                              2SB 4B 1OD 5SB                                                                               9.5BS                                                                              9.5BS                                                                              9RS                  "   0.5 + 2.0                                                                            1OD 5SB                                                                               1OD                                                                               1OD 1OD 9BS 9BS 3CSB                                                                               5B 1OD 4SB                                                                               9BS 9BS 9RS                  "   1.0 + 0.25                                                                           10D 2S 1OD                                                                               1OD 1OD 9.5BS                                                                              9.5BS                                                                              3SB 4B 1OD 2S 9.5BS                                                                              9.5BS                                                                              1ON                  "   1.0 + 0.5                                                                            1OD 4SB                                                                               1OD                                                                               1OD 1OD 9.5BS                                                                              9.5BS                                                                              7BS 9B 1OD 4SB                                                                               1OD 1OD 9.5RS                "   1.0 + 1.0                                                                            1OD 7SB                                                                               1OD                                                                               1OD 1OD 9.5BS                                                                              9.5BS                                                                              1OD 9B 1OD 8BS                                                                               9BS 1OD 9.5RS                "   1.0 + 2.0                                                                            1OD 4SB                                                                               1OD                                                                               1OD 1OD 9.5BS                                                                              9.5BS                                                                              1OD 9.5B                                                                              1OD 7BS                                                                               9.5BS                                                                              1OD 9.5RS                "   2.0 + 0.25                                                                           1OD 5SB                                                                               1OD                                                                               1OD 1OD 9.5BS                                                                              10D 9BS 9B 1OD 4SB                                                                               9.5BS                                                                              1OD 1ON                  "   2.0 + 0.5                                                                            1O  7SB                                                                               1OD                                                                               1OD 1OD 9.5BS                                                                              9.5BS                                                                              9.5B                                                                               9B 1OD 6SB                                                                               9.5BS                                                                              1OD 9.5RS                A + B                                                                              2.0 + 1.0                                                                            1OD 7SB                                                                               1OD                                                                               1OD 1OD 9.5BS                                                                              1OD 1OD 9.5B                                                                              1OD 6SB                                                                               9.5BS                                                                              1OD 1ON                  "   2.0 + 2.0                                                                            1OD 7SB                                                                               1OD                                                                               10D 10D 9.5BS                                                                              1OD 9B  9.5B                                                                              1OD 8BS                                                                               9.5BS                                                                              1OD 1ON                  Con-                                                                               0     0   0  0  0   0   0   0   0   0  0   0  0   0   0                    trol                                                                           __________________________________________________________________________

                                      TABLE XII:                                   __________________________________________________________________________     COMBINATION OF 1-METHOXY-6-CHLORO-2-TRIFLUOROMETHYL-                           1H-IMIDAZO(4,5-b)PYRIDINE ("A") WITH EPTC ("B")                                                 Fox-                                                              Rates Morn-  tail    Barn-                                                                              Large          Vel-   Jim-                                                                               John-                                                                              Lambs               Com-                                                                               Lbs./ ing    Mil-                                                                               Rag yard                                                                               Crab-                                                                              Pig-                                                                               Sor-   vet    son son Quar-               pounds                                                                             Acre  Glory                                                                              Corn                                                                              let weed                                                                               Grass                                                                              grass                                                                              weed                                                                               ghum                                                                               Rice                                                                              Leaf                                                                               Corn                                                                              Weed                                                                               Grass                                                                              ter                 __________________________________________________________________________     A + B                                                                              0.25 + 1.0                                                                           1OD 3S 9BS 8SB 7BS 6BS 8SB 1OD 8S 1OD 0  8BS 1OD 9.5 RS              "   0.25 + 2.0                                                                           1OD 2S 9BS 1OD 9BSF                                                                               9.5RSB                                                                             1ON 1OD 1ON                                                                               1OD 4S 9BS 1OD 1ON                 "   0.25 + 3.0                                                                           1OD 7FS                                                                               9.5BS                                                                              1OD 9BSF                                                                               1OD 1ON 1OD 9.8RS                                                                             10D 4S 1OD 1ON 1ON                 "   0.25 + 4.0                                                                           1OD 8FS                                                                               1OD 1OD 9BSF                                                                               1OD 1ON 1OD 1ON                                                                               1OD 7FS                                                                               9BSR                                                                               1ON 9.5RS               "   0.5 + 1OD0                                                                               1S 1OD 1OD 8BS 7BS 1OD 1OD 8BSR                                                                              1OD 4S 9BS 1OD 1ON                 "   0.5 + 2.0                                                                            1OD 5SF                                                                               1OD 1OD 9.5BSR                                                                             1OD 1ON 9.8RSF                                                                             9.5RS                                                                             1OD 4S 9BS 1OD 1ON                 "   0.5 + 3.0                                                                            1OD 7FS                                                                               1OD 1OD 9.5BSF                                                                             1OD 1ON 1OD 1ON                                                                               1OD 6SF                                                                               9.5BS                                                                              1OD 9.8RS               "   0.5 + 4.0                                                                            1OD 8FS                                                                               1OD 1OD 9.8BS                                                                              1ON 1ON 1OD 1ON                                                                               1OD 8FS                                                                               9BS 1OD 1ON                 "   1.0 + 1.0                                                                            1OD 4S 1OD 1OD 9.8BS                                                                              9.5BS                                                                              9.5BSR                                                                             1OD 8SB                                                                               9.5BS                                                                              4S 9.5BS                                                                              9.5BS                                                                              9RS                 "   1.0 + 2.0                                                                            1OD 8SB                                                                               10D 1OD 1OD 1OD 1ON 1OD 1OD                                                                               1OD 5S 9BS 1OD 9.5RS               "   1.0 + 3.0                                                                            1OD 7SBF                                                                              1OD 1OD 1OD 1OD 1OD 1OD 1ON                                                                               1OD 8BSF                                                                              9.5BS                                                                              1OD 9.5RS               "   1.0 + 4.0                                                                            1OD 7SB                                                                               1OD 1OD 1OD 1OD 1ON 1OD 1OD                                                                               1OD 8SBF                                                                              1OD 1OD 9.8RS               "   2.0 + 1.0                                                                            1OD 7SB                                                                               1OD 10D 1OD 1OD 9.5RSB                                                                             1OD 8SB                                                                               1OD 7SB                                                                               9BS 1OD 9.5RS               "   2.0 + 2.0                                                                            1OD 8SB                                                                               1OD 9SB 1OD 1OD 9.5RSB                                                                             10D 1OD                                                                               1OD 7SB                                                                               1OD 1OD 1ON                 "   2.0 + 3.0                                                                            1OD 1OD                                                                               1OD 1OD 1OD 1OD 1ON 1OD 1ON                                                                               9.8BSR                                                                             9SB                                                                               1OD 1OD 9.8RS               "   2.0 + 4.0                                                                            1OD 1OD                                                                               1OD 1ON 1OD 1OD 1ON 1OD 1OD                                                                               1OD 9BS                                                                               9.5BS                                                                              1OD 9.8RS               Control                                                                            0     0   0  0   0   0   0   0   0   0  0   0  0   0   0                   __________________________________________________________________________

                                      TABLE XIII                                   __________________________________________________________________________     COMBINATION OF 1-METHOXY-6-CHLORO-2-TRIFLUOROMETHYL-                           1H-IMIDAZO(4,5-b)PYRIDINE ("A") WITH LINURON ("B")                                               Fox-                                                              Rates Morn-  tail   Barn-                                                                              Large          Vel-   Jim-                                                                               John-                                                                              Lambs               Com- Lbs./ ing    Mil-                                                                              Rag-                                                                               yard                                                                               Crab-                                                                              Dig-                                                                               Sor-   vet    son son Quar-               pounds                                                                              Acre  Glory                                                                              Corn                                                                              let                                                                               weed                                                                               Grass                                                                              grass                                                                              weed                                                                               ghum                                                                               Rice                                                                              Leaf                                                                               Corn                                                                              Weed                                                                               Grass                                                                              ter                 __________________________________________________________________________     A + B                                                                               0.25 + 0.25                                                                          2SBC                                                                               2SB                                                                               8BS                                                                               1OD 4BS 5S  9SB 0   2B 9BS 0  8BS 2SB 9.5RS               "    0.25 + 0.5                                                                           3SB 0  8BS                                                                               7BS 8BS 5S  9SB 0   2B 1OD 0  8BS 9BS 1OD                 "    0.25 + 1.0                                                                           4SB 0  1OD                                                                               9BS 1OD 9BS 1OD 3BS 4B 1OD 0  9BS 9BS 9SR                 "    0.25 + 2.0                                                                           9BS 3S 1OD                                                                               1OD 9.5BS                                                                              9BS 9S  4SB 4B 1OD 4BS                                                                               8BS 9BS 8SR                 "    0.5 + 0.25                                                                           1OD 3B 8BS                                                                               9BS 8BS 7SB 9BS 3B  3B 9BS 1S 9BS 7BS 9SRB                "    0.5 + 0.5                                                                            5SB 0  8BS                                                                               9BS 9BS 7BS 1OD 2S  2B 1OD 0  9BS 9BS 9SR                 "    0.5 + 1.0                                                                            9BS 0  1OD                                                                               9BS 9BS 8BS 9S  3S  3B 1OD 2S 8BS 8BS 9SR                 "    0.5 + 2.0                                                                            1OD 3S 1OD                                                                               1OD 1OD 9.5BS                                                                              9.5BS                                                                              3SB 4B 1OD 3S 9BS 9.5BS                                                                              9SR                 "    1.0 + 0.25                                                                           1OD 2S 1OD                                                                               1OD 9.5BS                                                                              9.5BS                                                                              9.5BS                                                                              4SB 3B 9.5BS                                                                              2S 9.5BS                                                                              9.5BS                                                                              9SR                 "    1.0 +0.5                                                                             1OD 3S 1OD                                                                               1OD 1OD 9BS 9.5BS                                                                              8B  4B 1OD 3S 9.5BS                                                                              1OD 9.5RS               "    1.0 + 1.0                                                                            1OD 4SB                                                                               1OD                                                                               1OD 1OD 9.5BS                                                                              9.5BS                                                                              9BS 5B 1OD 3S 9.5BS                                                                              9.5BS                                                                              9.5RS               "    1.0 + 2.0                                                                            1OD 6SB                                                                               1OD                                                                               1OD 1OD 9.5BS                                                                              9.5BS                                                                              9.5BS                                                                              6B 1OD 5SB                                                                               9.5BS                                                                              1OD 1OD                 "    2.0 + 0.25                                                                           1OD 5S 1OD                                                                               1OD 1OD 9.5BS                                                                              9.5BS                                                                              9.5BS                                                                              9B 1OD 5SB                                                                               1OD 1OD 9.5RS               "    2.0 + 0.5                                                                            1OD 5SB                                                                               1OD                                                                               1OD 1OD 9.5BS                                                                              9.5BS                                                                              9.5BS                                                                              8B 1OD 7SB                                                                               9.5BS                                                                              9.5BS                                                                              9.5RS               "    2.0 + 1.0                                                                            1OD 6SB                                                                               1OD                                                                               1OD 1OD 9.5BS                                                                              1OD 9B  8B 1OD 5SB                                                                               9.5BS                                                                              9.5BS                                                                              9.5RS               "    2.0 + 2.0                                                                            1OD 7SB                                                                               1OD                                                                               1OD 1OD 9.5BS                                                                              9.5BS                                                                              1OD 9BS                                                                               1OD 6SB                                                                               1OD 1OD 9.5RS               Control                                                                             0     0   0  0  0   0   0   0   0   0  0   0  0   0   0                   __________________________________________________________________________

                                      TABLE XIV                                    __________________________________________________________________________     COMBINATION OF 1-METHOXY-6-CHLORO-2-TRIFLUOROMETHYL-                           1H-IMIDAZO(4,5-b)PYRIDINE ("A") WITH ORYZALIN ("B")                                                                               Fox-                            Rates                                                                              Morn-               Lambs    Barn-  Large  tail    John-               Com-                                                                               Lbs./                                                                              ing Pig-                                                                               Rag-   Velvet                                                                              Quar-                                                                              Jimson                                                                              yard   Crab-  Mil-                                                                               Sor-                                                                               son                 pounds                                                                             Acre                                                                               Glory                                                                              weed                                                                               weed                                                                               Corn                                                                              Leaf ter Weed Grass                                                                              Rice                                                                              grass                                                                              Corn                                                                              let ghum                                                                               Grass               __________________________________________________________________________     A+B 1/4                                                                              1/2                                                                              5S  6S  5S  6.5                                                                               5.5CS                                                                               ION 3CS  7RS 6.5                                                                               9.5RS                                                                              5CS                                                                               8.5SD                                                                              7BS 6.5BS                                   BS                   CS                                    "   1/4                                                                              1 5S  7.5RS                                                                              6.5 7.5                                                                               6CS  9.5RS                                                                              6S   8.5RS                                                                              8CS                                                                               9.5RS                                                                              7BS                                                                               9SD 7.5BS                                                                              7BS                                 CRS BS                                                         "   1/4                                                                              2 9BSD                                                                               9RS 8RS 8BS                                                                               7CS  1ON 6.5S 9RS 8CS                                                                               1ON 8BS                                                                               9.5RS                                                                              8BPS                                                                               8BSD                "   1/4                                                                              4 9.5 9RS 8.5RS                                                                              9BS                                                                               9BS  1ON 7BS  9.5RS                                                                              9BS                                                                               1ON 9BS                                                                               1OD 9BS 8.5                         BSD                                                BSD                 "   1/2                                                                              1/2                                                                              8BSD                                                                               8RS 8.5 6BS                                                                               5CBS 9a.5RS                                                                             5S   6.5RS                                                                              6.5                                                                               9RS 5BS                                                                               9BSD                                                                               6.5RS                                                                              7BSD                                BSD                      CS                                    "   1/4                                                                              1 9.5 9.5RS                                                                              9BS 7BS                                                                               6.5BS                                                                               1ON 9BSD 9RS 7.5                                                                               1ON 7BS                                                                               1OD 7BS 8SD                         BSD                              BSC                                   "   1/2                                                                              2 9.5 9.5RS                                                                              9BSD                                                                               7BS                                                                               8.5BSD                                                                              1ON 8BSD 9.5RS                                                                              8.5                                                                               1ON 8BS                                                                               9.5SD                                                                              8.5BS                                                                              8BSD                        BSD                              BS                                    "   1/2                                                                              4 1OD 9.5RS                                                                              9.5SD                                                                              8BS                                                                               8.5BSD                                                                              1ON 9BSD 1OD 8.5                                                                               1ON 7.5                                                                               1ON 9BS 8BSD                                                         BS     BS                             "   1 ;178                                                                             1OD 9RS 9.5SD                                                                              4S 6BSD 9.5RS                                                                              9.5BSD                                                                              9SD 7BS                                                                               9.5SD                                                                              4S 1OD 7BS 9BSD                "   1 1 1OD 9RS 9.5SD                                                                              7BS                                                                               7BSD 1ON 9.5BSD                                                                              9SD 7BS                                                                               9.5RS                                                                              6S 9SD 5BS 9BSD                "   1 2 9.5 1ON 9.5 7BS                                                                               9.5BSD                                                                              1ON 9BSD 1OD 8BS                                                                               1ON 7.5                                                                               1OD 9SD 9.5SD                       BSD     BSD                             BS                             "   1 4 1OD 1ON 1OD 7BS                                                                               9.5BSD                                                                              1ON 9.5BSD                                                                              1OD 8.5                                                                               1ON 8.5                                                                               1OD 9BSD                                                                               9.5                                                          BS     BS         BSD                 "   2 1/2                                                                              1OD 9.5RS                                                                              9.5SD                                                                              2.5                                                                               1OD  1ON 9.5SD                                                                               9.5RS                                                                              7SD                                                                               1ON 3S 1OD 7BS 1OD                                     BS                                                         "   2 1 1OD 9.5SD                                                                              9.5SD                                                                              4BS                                                                               1OD  9.5RS                                                                              9.5SD                                                                               1OD 8  1ON 4.5                                                                               1OD 7.5 1OD                                                          BSD    BS     BSD                     "   2 2 1OD 1ON 9.5SD                                                                              6.5                                                                               1OD  1ON 1OD  1OD 8  9.5SD                                                                              5.5S                                                                              1OD 7.5 9.5SD                                   BS                   BSD           BSD                     "   2 4 9.5SD                                                                              1OD 1OD 3.5S                                                                              9.5SD                                                                               1ON 1OD  1OD 6.5                                                                               1ON 5.5S                                                                              1OD 8.5 1OD                                                          BS            BSD                     Con-                                                                           trol                                                                               --                                                                               --                                                                               0   0   0   0  0    0   0    0   0  0   0  0   0   0                   __________________________________________________________________________

                                      TABLE XV:                                    __________________________________________________________________________     COMBINATION OF 1-METHOXY-6-CHLORO-2-TRIFLUOROMETHYL-                           1H-IMIDAZO(4,5-6)PYRIDINE ("A") WITH PROPACHLOR ("B")                               Rates Mor-   Fox-    Barn-                                                                              Large           Vel-  Jim-                                                                              John-                                                                              Lambs               Com- Lbs./ ning   tail                                                                               Rag-                                                                               yard                                                                               Crab-                                                                              Pig-                                                                               sor-    vet   son                                                                               son Quar-               pounds                                                                              Acre  Glory                                                                              Corn                                                                              Millet                                                                             weed                                                                               Grass                                                                              grass                                                                              weed                                                                               ghum                                                                               Rice                                                                               Leaf                                                                              Corn                                                                              Weed                                                                              Grass                                                                              ter                 __________________________________________________________________________     A+B     0.25 + 1.0                                                                        7BS 0  1OD 1OD 9RS 8RS 1OD 2B  9RS 6SB                                                                               0  1OD                                                                               4SR 7RS                 "       0.25 + 2.0                                                                        1OD 0  1OD 1OD 9RS 8RS 5SB 3SB 9RS 7BS                                                                               0  9BS                                                                               3S  6RS                 "       0.25+ 3.0                                                                         9BS 0  1OD 1OD 9RS 1OD 1OD 4S  1ON 9BSR                                                                              0  9BS                                                                               4S  7S                  "       0.25 + 4.0                                                                        1OD  1S                                                                               1OD 1OD 9RS 8S  7SR 4S  1ON 9BS                                                                               0  8BS                                                                               4S  7S                  "       0.5 + 1.0                                                                         9BS 0  1OD 1OD 8RSB                                                                               8S  7RS 3BS 8BS 8BS                                                                               0  8BS                                                                               5SB 8SB                 "       0.5 + 2.0                                                                         1OD 0  1OD 1OD 9BSR                                                                               8S  8SR 2SB 9RS 9BS                                                                               0  9BS                                                                               6SB 8SR                 "       0.5 + 3.0                                                                         1OD 0  1OD 1OD 9BSR                                                                               8SR 8SR 4S  9RS 9BS                                                                               0  9BS                                                                               5S  7S                  "       0.5 + 4.0                                                                         1OD 0  1OD 1OD 1OD 1ON 1ON 4S  9RS 9BS                                                                               2S 9BS                                                                               6SB 8S                  "       1.0 + 1.0                                                                         1OD 0  1OD 1OD 1OD 1ON 1OD 6BS 5SB 9BS                                                                               0  9BS                                                                               9BS 9RS                 "       1.0 + 2.0                                                                         1OD  2S                                                                               1OD 1OD 1OD 9.5RS                                                                              1ON 5BS 5SB 9BS                                                                               0  1OD                                                                               9.5BS                                                                              8SR                 "       1.0 + 3.0                                                                         1OD 0  1OD 1OD 9BSR                                                                               9RS 9BSR                                                                               6BS 9RS 1OD                                                                               1S 9BS                                                                               9.5BS                                                                              8S                  "       1.0 + 4.0                                                                         1OD 0  1OD 1OD 1OD 1ON 1ON 4SB 9RS 1OD                                                                               0  9BS                                                                               9.5BS                                                                              9SR                 "       2.0 + 1.0                                                                         1OD  3S                                                                               1OD 1OD 1OD 1OD 1OD 9BS 7BS 1OD                                                                               3S 9BS                                                                               9BS 9RS                 "       2.0 + 2.0                                                                         1OD  4S                                                                               1OD 1OD 1OD 1OD 9SR 8BS 9RS 1OD                                                                               5SB                                                                               9BS                                                                               1OD 9S                  "       2.0 + 3.0                                                                         1OD  3S                                                                               1OD 1OD 1OD 1ON 1ON 9BS 8RS 1OD                                                                               4S 9BS                                                                               1OD 9SR                 "       2.0 + 4.0                                                                         1OD  1S                                                                               1OD 1OD 1OD 1OD 9.8BSR 9BS                                                                         1ON 1OD 3S 1OD                                                                               1OD                                                                               1ON                     Control 0  0   0  0   0   0   0   0   0   0   0  0  0  0   0                   __________________________________________________________________________

                                      TABLE XVI:                                   __________________________________________________________________________     COMBINATION OF 1-METHOXY-6-CHLORO-2-TRIFLUOROMETHYL-1H-                        IMIDAZO(4,5-b)PEPIDINE ("A") WITH PROPAZINE ("B")                              __________________________________________________________________________                                                         Fox-                           Rates                                                                              Morn-           Vel-                                                                               Lambs                                                                              Jim-                                                                               Barn-   Large   tail  John-                Com-                                                                               Lbs./                                                                              ing Pig-                                                                               Rag-                                                                               Sor-                                                                               vet Quar-                                                                              son yard    Crab                                                                               Sor-                                                                               Mil-  son                  pounds                                                                             Acre                                                                               Glory                                                                              weed                                                                               weed                                                                               ghum                                                                               Leaf                                                                               ter Weed                                                                               Grass                                                                              Rice                                                                               grass                                                                              ghum                                                                               let                                                                               Corn                                                                              Grass                __________________________________________________________________________     A + B                                                                              1/2                                                                              3/4                                                                              8DS 8SD 8BSD                                                                               0   3BSD                                                                               9RSD                                                                               9.5SD                                                                              5SD 2BS 3S  0   6  0  8BSD                                                                     BSD                        "   1/2                                                                              11/2                                                                             8.5 8SD 9BSD                                                                               0   5BSD                                                                               9RSD                                                                               9BSD                                                                               4SD 3BS 4.5RS                                                                              0   7  0  7BSD                         BSD                                         BSD                        "   1/2                                                                              3 8.5 8.5SD                                                                              9BSD                                                                               0   3CS 8RSD                                                                               9.5 8BSD                                                                               5BS 7.5 0   6  0  7.5BSD                       BSD                     BSD         RSD     BSD                        "   1 3/4                                                                              1OD 8.5SD                                                                              9BSD                                                                               3BS 7.5 8RSD                                                                               9.5SD                                                                              7BSD                                                                               1BS 9RSD                                                                               0   9.5                                                                               2S 9.5BSD                                       BSD                         SD                         "   1 11/2                                                                             1OD 8SD 9.5 3BS 1OD 9RSD                                                                               9.5 8.5 2BS 8RSD                                                                               2BS 1OD                                                                               0  9.5BSD                               BSD             BSD BSD                                        "   1 3 1OD 8.5SD                                                                              1OD 2BS 1OD 9RSD                                                                               9.5 9.5 4BS 9RSD                                                                               1BS 9SD                                                                               0  9.5BSD                                               BSD BSD                                        "   11/2                                                                             3/4                                                                              1OD 8SD 8BSD                                                                               2BS 8BSD                                                                               9RSD                                                                               9.5SD                                                                              1OD 6BSD                                                                               9.5 2BS 1OD                                                                               0  1OD                                                              RSD                                "   11/2                                                                             11/2                                                                             9.5 8BSD                                                                               1OD 2.5BS                                                                              9.5 9RSD                                                                               9.5 9BSD                                                                               5BSD                                                                               1OD 2BS 1OD                                                                               2BS                                                                               9.5BSD                       BSD             BSD     BSD                                            "   11/2                                                                             3 1OD 8BSD                                                                               1OD 3BS 1OD 9RSD                                                                               1OD 9.5 7BSD                                                                               8SD 3.5BS                                                                              1OD                                                                               1S 9.5BSD                                                   BSD                                        "   2 3/4                                                                              1OD 8BSD                                                                               9BSD                                                                               3BS 9.5 9RSD                                                                               9.5 9.5 5BSD                                                                               9.5SD                                                                              4BS 1OD                                                                               2S 1OD                                          BSD     BSD BSD                                        "   2 11/2                                                                             1OD 8BSD                                                                               9.5 2BS 1OD 9.5 1OD 1OD 6.5 1OD 3BS 1OD                                                                               1S 9BSD                                 BSD         RSD         BSD                                    "   2 3 1OD 8.5 1OD 2BS 9BSD                                                                               9.5 9.5 10D 6BSD                                                                               9RSD                                                                               2BS 1OD                                                                               0  1OD                              BSD             RSD BSD                                            Con-                                                                               --                                                                               --                                                                               0   0   0   0   0   0   0   0   0   0   0   0  0  0                    trol                                                                           Con-                                                                               --                                                                               --                                                                               0   0   0   0   0   0   0   0   0   0   0   0  0  0                    trol                                                                           Con-                                                                               --                                                                               --                                                                               0   0   0   0   0   0   0   0   0   0   0   0  0  0                    trol                                                                           __________________________________________________________________________

                                      TABLE XVII:                                  __________________________________________________________________________     COMBINATION OF 1-METHOXY-6-CHLORO-2-TRIFLUOROMETHYL-                           1H-IMIDAZO(4,5-b)PYRIDINE ("A") WITH SIMAZINE ("B")                            __________________________________________________________________________         Rates                                                                              Morn-          Vel-                                                                               Lambs   Barn-   Large   Fox-    John-               Com-                                                                               Lbs./                                                                              ing Pig-                                                                               Rag-   vet Quar-                                                                              Jimson                                                                             yard    Crab-   tail                                                                               Sor-                                                                               son                 pounds                                                                             Acre                                                                               Glory                                                                              weed                                                                               weed                                                                               Corn                                                                              Leaf                                                                               ter Weed                                                                               Grass                                                                              Rice                                                                               grass                                                                              Corn                                                                               millet                                                                             ghum                                                                               Grass               __________________________________________________________________________     A+B 1/4                                                                              1/4                                                                              6.5 8.5BS                                                                              6.5SD                                                                              0  2S  6.5S                                                                               9.5SD                                                                              0   1BS 6BS 0   4.5BS                                                                              0   4BS                         BSD                                                                    "   1/4                                                                              1/2                                                                              1OD 7BSD                                                                               7RSD                                                                               0  5CS 1OD 1OD 6BSD                                                                               2BS 7.5BS                                                                              0   6BS 0   7BSD                "   1/4                                                                              1 1OD 8.5 9SD 0  6CS 9SD 9.5SD                                                                              8BSD                                                                               2BS 9BSD                                                                               0   7BSD                                                                               0   9BSD                            BSO                                                                "   1/4                                                                              2 1OD 8.5 9SD 0  8SD 9.5SD                                                                              1OD 9.5 3BS 9BSD                                                                               6BSD                                                                               9.5 2S  9BSD                            BSD                    BSD             BSD                         "   1/2                                                                              1/4                                                                              1OD 8BS 8BSD                                                                               0  5CS 9BSD                                                                               9SD 3BS 1B  6SD 0   7.5 0   8.5                                                                    BSD     BSD                 "   1/2                                                                              1/2                                                                              9.5 8.5BS                                                                              9.5SD                                                                              0  6.5 9BSD                                                                               9.5SD                                                                              3BS 6.5BS                                                                              8SD 0   8BSD                                                                               0   9BSD                        BSD            BSD                                                     "   1/2                                                                              1 9.5 9BS 9.5SD                                                                              0  6.5 1OD 1OD 3.5BS                                                                              5BS 9SD 0   9.5 0   9.5                         BSD            BSD                         BSD     BSD                 "   1/2                                                                              2 1OD 9.5BS                                                                              1OD 0  7CSD                                                                               1OD 1OD 9.5BS                                                                              5BS 9.5SD                                                                              0   1OD 4BS 9.5                                                                            BSD                 "   1 1/4                                                                              9.5 9BS 9SD 0  7SD 9BS 1OD 7BSD                                                                               3BS 9BSD                                                                               0   9BSD                                                                               0   1OD                         BSD                                                                    "   1 1/2                                                                              1OD 6.5S                                                                               9SD 1S 6SD 9BS 9.5 9.5 2BS 9.5 1.5S                                                                               9.5 3BS 1OD                                                BSD BSD     BSD     BSD                         "   1 1 1OD 8S  1OD 0  7SD 7.5BS                                                                              9.5 9.5 6BS 1OD 0   9.5 3BS 1OD                                                BSD BSD             BSD                         "   1 2 1OD 9.5BS                                                                              8SD 1S 9SD 1OD 1OD 9BSD                                                                               4BS 1OD 1.5S                                                                               1OD 5BS 1OD                 "   2 1/4                                                                              1OD 9BSD                                                                               9.5 1.5S                                                                              1OD 1OD 1OD 9BSD                                                                               6BSD                                                                               9.5 0   1OD 3BS 1OD                                 BSD                        BSD                                 "   2 1/2                                                                              1OD 9.5 9.5 2S 9.5 9BS 9.5SD                                                                              9BSD                                                                               6BSD                                                                               9.5 1.5S                                                                               1OD 5BS 9.5                             BSD BSD    BSD                 BSD             BSD                 "   2 1 1OD 9.5 9.5 1S 9BSD                                                                               9.5BS                                                                              1OD 9.5 6BSD                                                                               1OD 1S  1OD 4.5BS                                                                              9.5                             BSD BSD                BSD                     BSD                 "   2 2 9.5 9BSD                                                                               9.5 1.5S                                                                              9.5 1OD 1OD 9.5 6BSD                                                                               1OD 1S  1OD 6BS 9.5                         BSD     BSD    BSD         BSD                     BSD                 Con-                                                                           trol                                                                               --                                                                               --                                                                               0   0   0   0  0   0   0   0   0   0   0   0   0   0                   __________________________________________________________________________

                                      TABLE XVIII                                  __________________________________________________________________________     COMBINATION OF 1-METHOXY-6-CHLORO-2-TRIFLUOROMETHYL-                           1H-IMIDAZO(4,5-b)PYRIDINE ("A") WITH TRIFLURALIN ("B")                                   Morn-         Barn-                                                                              Large                      John-                                                                              Lambs               Com-                                                                               Rates ing    Foxtail                                                                            Rag-                                                                              yard                                                                               Crab-                                                                              Pig-                                                                              Sor-    Velvet  Jimson                                                                             son Quart-              pounds                                                                             Lbs./Acre                                                                            Glory                                                                              Corn                                                                              Millet                                                                             weed                                                                              Grass                                                                              grass                                                                              weed                                                                              ghum                                                                               Rice                                                                               Leaf                                                                               Corn                                                                               Weed                                                                               Grass                                                                              er                  __________________________________________________________________________     A + B                                                                              0.21                                                                              0.25                                                                              6SB 0  8SR                                                                               5S  9RS 10N 10N                                                                               8SR 5SC 0   0   2S  5SR 4S                  "   "  0.5                                                                               8SB 0  9SR                                                                               10D 9RS 9.5RS                                                                              10N                                                                               7SR 6SC 3SB 0   5SB 4S  5S                  "   "  1.0                                                                               10D 0  9BSR                                                                              10D 9RSB                                                                               9.5RS                                                                              9.5                                                                               9SR 5SCB                                                                               8BS 2S  8BS 9.5RS                                                                              9BSR                                                BS                                             "   "  2.0                                                                               10D 5S 10N                                                                               10D 9.5RS                                                                              9.5RS                                                                              10N                                                                               8SR 5SB 10D 4S  9BSR                                                                               10N 10N                 "   0.42                                                                              0.25                                                                              5SB 4S 9RSB                                                                              5SB 10N 10N 10N                                                                               10N 8SC 2S  4SC 2SC 9.5RS                                                                              6SR                 "   "  0.5                                                                               6BS 5S 9.8RS                                                                             10D 9.5RS                                                                              9.5RS                                                                              10N                                                                               10N 9SC 3S  4S  5SB 10N 8SR                 "   "  1.0                                                                               10D 4S 9.8RS                                                                             10D 10N 10N 10N                                                                               9.8RS                                                                              8SC 10D 5SB 9BS 9.5RS                                                                              9RS                 "   "  2.0                                                                               10D 5S 10N                                                                               10D 10N 10N 10N                                                                               10N 8SCR                                                                               10D 5SC 9BS 9.5RS                                                                              10N                 "   0.83                                                                              0.25                                                                              6SB 7  10N                                                                               7RS 9.5RS                                                                              10N 10N                                                                               10N 9CSR                                                                               3S  7CSF                                                                               3S  9.5RS                                                                              8RS                               FSC                                                              "   "  0.5                                                                               7BS 8  10N                                                                               10D 10N 10N 10N                                                                               9.9RS                                                                              9CSR                                                                               4SB 7CSF                                                                               8BSF                                                                               9.8RS                                                                              9.5RS                             RSF                                                              "   "  1.0                                                                               8SB 8  9.8RS                                                                             10D 9.8RS                                                                              10N 10N                                                                               10N 9SRF                                                                               7BS 7SC 9.5BS                                                                              9.9RS                                                                              9.5RS                             BSF                                                              "   "  2.0                                                                               9BS 8  10N                                                                               10D 10N 10N 10N                                                                               10N 9SCR                                                                               9.8BS                                                                              7SCB                                                                               9BSF                                                                               10N 9.5RS                             SCB                                                              "   2.0                                                                               0.25                                                                              7SB 9  10N                                                                               8   10N 10N 10N                                                                               10N 9.5SR                                                                              6S  9RSF                                                                               4SB 10N 10N                               RSF   BSR                                                        "   "  0.5                                                                               7SB 9  10N                                                                               9.5 10N 10N 10N                                                                               10N 9.8RS                                                                              5SF 8FSB                                                                               6SF 10N 10N                               RSB   BS                                                         "   "  1.0                                                                               10D 9  10N                                                                               10D 10N 10N 8SR                                                                               10N 9RS 10D 9SF 9.5BS                                                                              10N 9.5RS                             FSB                                                              "   "  2.0                                                                               10D 9  10N                                                                               10D 10N 10N 9.5                                                                               10N 9.5SR                                                                              9.5BS                                                                              9FSB                                                                               10D 10N 10N                               FSB               RS                                             Con-                                                                               0     0   0  0  0   0   0   0  0   0   0   0   0   0   0                   trol                                                                           __________________________________________________________________________

                                      TABLE XIX                                    __________________________________________________________________________     COMBINATION OF 1-METHOXY-6-CHLORO-2-TRIFLUOROMETHYL-                           1H-IMIDAZO(4,5-b)PYRIDINE ("A") WITH TCA ("B")                                     Rates                                                                              Morn-            Lambs   Barn-   Large                                 Com-                                                                               Lbs./                                                                              ing Pig-                                                                              Rag-  Velvet                                                                             Quart-                                                                             Jimson                                                                             yard    Crab-  Foxtail   Johnson              pounds                                                                             Acre                                                                               Glory                                                                              weed                                                                              weed                                                                              Corn                                                                              Leaf                                                                               er  Weed Grass                                                                         Rice                                                                               grass                                                                              Corn                                                                               Millet                                                                            Sorghum                                                                             Grass                     __________________________________________________________________________     A + B                                                                              1/4                                                                              3/4                                                                              2CS -- -- 1S 0   0   2.5S                                                                               1S  0   1S  0  4BFD 0    3BS                  "   1/4                                                                              11/2                                                                             2CS -- -- 2S 0   2S  4S  0   5BS 8SD 0  7BFD 0    3BS                  "   1/4                                                                              3 2CS -- -- 1S 0   3RS 2S  2S  9BSD                                                                               9BSD                                                                               0  9BFD 0    4BS                  "   1/4                                                                              6 1C  -- -- 1S 0   3S  3S  7BFS                                                                               10D 7BSD                                                                               0  9.5BFD                                                                              7BFD 8BSD                 "   1/2                                                                              3/4                                                                              3BS -- -- 0  0   2S  7BSD                                                                               3S  6BSD                                                                               5BS 0  8.5BSD                                                                              0    4BS                  "   1/2                                                                              11/2                                                                             5BS -- -- 0  4CS 3S  6BSD                                                                               4BS 5BS 3BS 0  7BSD 0    8BSD                 "   1/2                                                                              3 4BSD                                                                               -- -- 0  5CBS                                                                               8RS 10D 8BSD                                                                               8BS 5SD 0  7BFSD                                                                               3BFS 9BSD                 "   1/2                                                                              6 7BSD                                                                               -- -- 3FS                                                                               6BSD                                                                               8RSD                                                                               9BSD                                                                               6BSD                                                                               8BSD                                                                               7BSD                                                                               2FS                                                                               9.5BSD                                                                              8BFSD                                                                               9BSD                 "   1 3/4                                                                              9BSD                                                                               -- -- 0  7BSD                                                                               7RS 9BSD                                                                               7BSD                                                                               3BS 6BSD                                                                               1S 8BSD 0    8BSD                 "   1 11/2                                                                             9BSD                                                                               -- -- 0  5BS 7RS 9.5 9BSD                                                                               8.5 9BSD                                                                               1.5S                                                                              9BSD 3BS  9BSD                                              BSD     BSD                                       "   1 3 5CBS                                                                               -- -- 0  6CBS                                                                               4RS 9BSD                                                                               6BSD                                                                               7BSD                                                                               9BSD                                                                               2S 10D  3BS  8BSD                 "   1 6 6   -- -- 1S 8BSD                                                                               8RS 9BSD                                                                               9BSD                                                                               9BSD                                                                               9BSD                                                                               0  9.5BSD                                                                              6BFS 10D                          BCSD -"                                                                            2  3/4                                                                               10D                                                                               --  --  2S  9BSD                                                                               7RS 9.5 9.5                                                                               6BSD 8BSD 1S 7BSD 3BS 9BSD                                                               3                                                 BSD BSD                                           "   2 11/2                                                                             10D -- -- 1S 9BSD                                                                               7RS 9.5 9.5 6BSD                                                                               9BSD                                                                               2S 10D  3BS  9.5BSD                                            BSD BSD                                           "   2 3 10D -- -- 3S 9BSD                                                                               8RS 9BSD                                                                               9.5 7BSD                                                                               8BSD                                                                               0  10D  6BSD 9.5BSD                                                BSD                                           "   2 6 10D -- -- 4FS                                                                               10D 9RS 9BSD                                                                               9.5 9BSD                                                                               8.5 3FS                                                                               10D  8.5BSFD                                                                             10D                                                   BSD     BSD                                   Con-                                                                               --                                                                               --                                                                               0   -- -- 0  0   0   0   0   0   0   0  0    0    0                    trol                                                                           __________________________________________________________________________

EXAMPLES 104-107

Additional evaluations were conducted, in accordance with the procedures of the foregoing examples, with 1-methoxy-5-chloro-2-trifluoromethyl-1H-imidazo(4,5-b)pyridine and with 1-methoxy-2,6-bis(trifluoromethyl)-1H-imidazo(4,5-)pyridine. Each was employed in combination with alachlor and separately in combination with atrazine. The results were as set forth in the following tables.

                                      TABLE XX:                                    __________________________________________________________________________     COMBINATION OF 1-METHOXY-5-CHLORO-2-TRIFLUOROMETHYL-                           1H-IMIDAZO(4,5-b)PYRIDINE ("A") WITH ALACHLOR ("B")                                             Fox-                                                              Rates Morn-  tail    Barn-                                                                              Large           Vel-   Jim-                                                                              John-                                                                              Lambs               Com-                                                                               Lbs./ ing    Mil-                                                                               Rag-                                                                               yard                                                                               Crab-                                                                              Pig-                                                                               Sor-    vet    son                                                                               son Quar-               pounds                                                                             Acre  Glory                                                                              Corn                                                                              let weed                                                                               Grass                                                                              grass                                                                              weed                                                                               ghum                                                                               Rice                                                                               Leaf                                                                               Corn                                                                              Weed                                                                              Grass                                                                              ter                 __________________________________________________________________________     A + B                                                                              0.25 + 0.5                                                                           3SE 2S 9.5BS                                                                              9.5RS                                                                              9.5RS                                                                              10D 9.5RS                                                                              9RSF                                                                               9RS  9.5 BS                                                                            0  9BS                                                                               9RSB                                                                               10D                 "   0.25 + 1.0                                                                           4SE 0  10D 10D 10D 10D 10D 9RSF                                                                               9.8RS                                                                              8BS 0  9.5-                                                                              9RSB                                                                               10D                                                                     BS                         "   0.25 + 2.0                                                                           6BSC                                                                               2S 10N 10N 10D 10N 10N 9.5BS                                                                              10N 9BS 1S 10D                                                                               9.5BS                                                                              10N                 "   0.25 + 4.0                                                                           9.5BS                                                                              0  10D 10D 10N 10N 10N 9.5BS                                                                              10N 9.5BS                                                                               3S                                                                               10D                                                                               10D 10D                 "   0.5 + 0.5                                                                            9.5BS                                                                              2BS                                                                               10D 9RS 9RSB                                                                               9.5RS                                                                              10N 8SFB                                                                               9.5RS                                                                              10D 2S 10D                                                                               8RSB                                                                               9.5RS               "   0.5 + 1.0                                                                            9BS 0  10D 10D 9.5RS                                                                              10D 10N 9.5BS                                                                              10N 10D 0  10D                                                                               8BSR                                                                               9RS                 "   0.5 + 2.0                                                                            10D 2S 10D 10D 10D 10N 10N 9.8BS                                                                              10N 10D 2S 10D                                                                               9.5R                                                                               9.5BS                                                                      SB                      "   0.5 + 4.0                                                                            10D 0  10N 10D 10N 10N 10N 10D 10N 10D 2S 10D                                                                               10D 10D                 "   1.0 + 0.5                                                                            10D 0  10D 10D 10D 10N 10D 9.8BS                                                                              9.5RS                                                                              10D 1S 10D                                                                               8RSB                                                                               10D                 "   1.0 + 1.0                                                                            10D 2S 10D 10D 10N 10N 9.5RS                                                                              8BSF                                                                               10D 10D 0  10D                                                                               9.5BS                                                                              9.5RS               "   1.0 + 2.0                                                                            10D 1S 10D 10D 10N 10N 10N 9.8BS                                                                              10N 10D 2S 10D                                                                               9.5BS                                                                              10N                 "   1.0 + 4.0                                                                            9.8BS                                                                              2SB                                                                               10N 10N 10N 10N 10N 9.8BS                                                                              10N 10D 2SB                                                                               10D                                                                               10D 10D                 "   2.0 + 0.5                                                                            10D 0  10D 10D 10D 10D 10D 9BSF                                                                               9RSB                                                                               10D 0  10D                                                                               9BSR                                                                               10D                 "   2.0 + 1.0                                                                            10D 2S 10D 10D 10D 10N 10D 10D 8RSB                                                                               10D 0  10D                                                                               10D 10D                 "   2.0 + 2.0                                                                            10D 3S 10N 10D 10N 10N 10N 10D 10N 10D 4SB                                                                               9BSR                                                                              9.5RS                                                                              10D                 "   2.0 + 4.0                                                                            10D 3S 10D 10N 10N 10N 10N 10D 10N 10D 2S 10D                                                                               9.5BS                                                                              10N                 Con-                                                                           trol                                                                               0     0   0  0   0   0   0   0   0   0   0   0  0  0   0                   __________________________________________________________________________

                                      TABLE XXI                                    __________________________________________________________________________     COMBINATION OF 1-METHOXY-5-CHLORO-2-TRIFLUOROMETHYL-                           1H-IMIDAZO(4,5-b)PYRIDINE ("A") WITH ATRAZINE ("B")                                Rates Morn-  Fox-   Barn-                                                                              Large           Vel-   Jim-                                                                               John-                                                                              Lambs               Com-                                                                               Lbs./ ing    tail                                                                               Rag-                                                                              yard                                                                               Crab                                                                               Pig-                                                                               Sor-    vet    son son Quar-               pounds                                                                             Acre  Glory                                                                              Corn                                                                              Millet                                                                             weed                                                                              Grass                                                                              grass                                                                              weed                                                                               ghum                                                                               Rice                                                                               Leaf                                                                               Corn                                                                              Weed                                                                               Grass                                                                              ter                 __________________________________________________________________________     A + B                                                                              0.25 + 0.25                                                                          7BS 1S 7BS 1OD                                                                               6SB 4SB 6SB 0   5B  8BS 0  1OD 0   7SB                 "   0.25 + 0.5                                                                           8BS 0  7BS 1OD                                                                               5SB 3SB 7SB 0   5B  9BS 0  9BS 0   7SB                 "   0.25 + 1.0                                                                           1OD 0  8BS 1OD                                                                               9BS 8BS 8BS 0   5B  1OD 0  1OD 2S  8BS                 "   0.25 + 2.0                                                                           1OD 0  9BS 1OD                                                                               8BS 7BS 7BS 0   9B  1OD 0  1OD 2SB 9BS                 "   0.5 + 0.25                                                                           9BS 0  9BS 1OD                                                                               7SB 8BS 8BS 0   8B  1OD 0  1OD 3SB 8BS                 "   0.5 + 0.5                                                                            1OD 0  1OD 1OD                                                                               7BS 5SB 8BS 1S  6B  7.5BS                                                                              0  1OD 3SB 9BS                 "   0.5 + 1.0                                                                            1OD 2C 9.5BS                                                                              1OD                                                                               7BS 6BS 8BS 2S  5B  1OD 3SC                                                                               9BS 3SC 1OD                 "   0.5 + 2.0                                                                            1OD 0  9.5BS                                                                              1OD                                                                               9BS 7BS 9BS 1S  9B  1OD 0  1OD 3S  9BS                 "   1.0 + 0.25                                                                           1OD 1S 9.5BS                                                                              1OD                                                                               9BS 6BS 9BS 2S  8B  1OD 0  1OD 3S  9BS                 "   1.0 + 0.5                                                                            1OD 2SB                                                                               1OD 1OD                                                                               9.5BS                                                                              7SB 8BS 3SB 9B  1OD 0  1OD 4SB 9BS                 "   1.0 + 1.0                                                                            1OD 1SB                                                                               1OD 1OD                                                                               9.5BS                                                                              9BS 9BS 3SB 1OD 1OD 0  1OD 4SB 9BS                 "   1.0 + 2.0                                                                            1OD 3S 10D 1OD                                                                               9BS 7BS 9BS 5SB 1OD 1OD 1S 1OD 3SB 9BS                 "   2.0 + 0.25                                                                           1OD 4SB                                                                               1OD 10D                                                                               9.5BS                                                                              8BS 9BS 8BS 1OD 1OD 3SB                                                                               1OD 9BS 9BS                 "   2.0 + 0.5                                                                            1OD 4SB                                                                               1OD 10D                                                                               9.5BS                                                                              9.5BS                                                                              9.5BS                                                                              8BS 9.5BS                                                                              1OD 3S 1OD 5SB 9BS                 "   2.0 + 1.0                                                                            1OD 6SB                                                                               1OD 1OD                                                                               9BS 9.5BS                                                                              9.5BS                                                                              8BS 1OD 1OD 2S 1OD 5SB 1OD                 "   2.0 + 2.0                                                                            1OD 3S 1OD 1OD                                                                               1OD 9.8BS                                                                              9.5BS                                                                              8SB 9B  1OD 3S 1OD 6SB 9BS                 Control                                                                            0     0   0  0   0  0   0   0   0   0   0   0  0   0   0                   __________________________________________________________________________

                                      TABLE XXII                                   __________________________________________________________________________     COMBINATION OF 1-METHOXY-2,6-BIS(TRIFLUOROMETHYL)-                             1H-IMIDAZO(4,5-b)PYRIDINE ("A") WITH ALACHLOR ("B")                                Rates Mor-   Fox-   Barn-                                                                              Large           Vel-   Jim-                                                                               John-                                                                              Lambs               Com-                                                                               Lbs./ ning   tail                                                                               Rag-                                                                              yard                                                                               Crab-                                                                              Pig-                                                                               Sor-    vet    son son Quar-               pounds                                                                             Acre  Glory                                                                              Corn                                                                              Millet                                                                             weed                                                                              Grass                                                                              grass                                                                              weed                                                                               ghum                                                                               Rice                                                                               Leaf                                                                               Corn                                                                              Weed                                                                               Grass                                                                              ter                 __________________________________________________________________________     A + B                                                                              0.25 + 0.5                                                                           2E  0  9.5BS                                                                               4SB                                                                              9RS 7RSB                                                                               8BSR                                                                               1S  5RB 4SB 0  3SB 4SR 9RS                 "   0.25 + 1.0                                                                           3SFE                                                                               0  10D 6SB                                                                               9.5RS                                                                              10D 10D 5SF 8RS 5SB 0  5SB 7RS 9RS                 "   0.25 + 2.0                                                                           5SEF                                                                               0  10D 9.5BS                                                                             10N 10D 10N 5SF 9RS 5SB 0  6SB 9RS 9RSB                "   0.25 + 4.0                                                                           7SBF                                                                               3SF                                                                               10N 9.5RS                                                                             10D 10D 10D 7SFB                                                                               10N 8SB 2S 8BS 10D 10N                 "   0.5 + 0.5                                                                            5SBF                                                                               0  10D 5SB                                                                               9RS 8RSB                                                                               10D 3SB 7SRB                                                                               7BS 0  8BS 7RSF                                                                               8SR                 "   0.5 + 1.0                                                                            6SBF                                                                               0  10D 7SR                                                                               9.5RS                                                                              10D 10D 3SF 9RSB                                                                               9.5BS                                                                              0  9BS 7RSB                                                                               9BSR                "   0.5 + 2.0                                                                            9.5BS                                                                              1S 10D 10N                                                                               10D 10N 10N 8BSF                                                                               9.5RS                                                                              9BS 1S 9BS 9.5BS                                                                              10N                 "   0.5 + 4.0                                                                            9.5BS                                                                              3S 10D 10D                                                                               10D 10D 10D 9.5BS                                                                              10N 9BS 4SF                                                                               10D 9.5BS                                                                              10N                 "   1.0 + 0.5                                                                            9.5BS                                                                              0  10D 6S 7SR 8RSB                                                                               10D 4SFB                                                                               4S  9BS 0  9BS 8BS 9RS                 "   1.0 + 1.0                                                                            8BS 0  10D 7RS                                                                               9RS 9RSB                                                                               10D 8BSF                                                                               9RS 9BS 0  9.5BS                                                                              9.5BS                                                                              9.5RS               "   1.0 + 2.0                                                                            9.5BS                                                                              3SB                                                                               10N 8RS                                                                               10D 10D 10N 8RSB                                                                               10N 9.5BS                                                                              3S 9.5BS                                                                              9.5RS                                                                              9.5RS               "   1.0 + 4.0                                                                            10N 0  10N 9SR                                                                               10N 10N 10D 9.5RS                                                                              10N 9BS 3S 9BS 10D 9.5RS               "   2.0 + 0.5                                                                            10D 0  10D 8BS                                                                               9RS 8BS 9BSR                                                                               8BS 8RS 9.5BS                                                                              2S 9BS 9BSR                                                                               9.5RS               "   2.0 + 1.0                                                                            10D 3S 10D 7S 9.5RSB                                                                             9.5BS                                                                              10D 8BS 9RS 9BS 1SB                                                                               9.5BS                                                                              9.5BS                                                                              9.5RS               "   2.0 + 2.0                                                                            10D 3S 10D 8SR                                                                               9.5BS                                                                              10D 10D 9BSF                                                                               9.5RS                                                                              9.5BS                                                                              4S 9.5BS                                                                              10D 10N                 "   2.0 + 4.0                                                                            10D 3BS                                                                               10N 10D                                                                               10N 10N 10N 9BSF                                                                               9.5RS                                                                              9.5BS                                                                              3S 9.5BS                                                                              10D 10N                 Control                                                                            0     0   0  0   0  0   0   0   0   0   0   0  0   0   0                   __________________________________________________________________________

                                      TABLE XXII                                   __________________________________________________________________________     COMBINATION OF 1-METHOXY-2,6-BIS(TRIFLUOROMETHYL)-                             1H-IMIDAZO(4,5-b)PYRIDINE ("A") + ATRAZINE ("B")                                                         Barn-                                                                              Large                   John-                    Com-                                                                               Rates  Morning Foxtail                                                                            Rag-                                                                              yard                                                                               Crab-                                                                              Pig-                                                                              Sor-  Velvet Jimson                                                                             son Lambs                pounds                                                                             Lbs./Acre                                                                             Glory                                                                               Corn                                                                              Millet                                                                             weed                                                                              Grass                                                                              grass                                                                              weed                                                                              ghum                                                                              Rice                                                                              Leaf                                                                               Corn                                                                              Weed                                                                               Grass                                                                              Quarter              __________________________________________________________________________     A + B                                                                              0.25 +                                                                             0.25                                                                              3BS  0  3B  2S 0   2S  5SB                                                                               0  2B 2S  0  2B  0   7BS                  "   0.25                                                                               0.5                                                                               5BS  0  4B  8BS                                                                               4S  4SB 6BS                                                                               0  3B 4SB 2S 8BS 0   8BS                  "   0.25                                                                               1.0                                                                               10D  0  7BS 8BS                                                                               3SB 4SB 8BS                                                                               1B 7B 10D 0  9BS 1B  8BS                  "   0.25                                                                               2.0                                                                               10D  0  9BS 10D                                                                               8BS 6BS 8BS                                                                               0  8B 10D 0  10D 2B  7BS                  "   0.5 +                                                                              0.25                                                                              9BS  0  3B  4BS                                                                               3SB 6BS 7SB                                                                               0  5B 4SB 2S 8BS 0   6SB                  "   0.5 0.5                                                                               9BS  0  4B  6S 4S  4S  6SB                                                                               0  6B 5SB 0  10D 2S  7SB                  "   0.5 1.0                                                                               10D  0  5BS 10D                                                                               4SB 5SB 7BS                                                                               0  7B 9BS 0  10D 0   7SB                  "   0.5 2.0                                                                               8BS  4SB                                                                               5BS 10D                                                                               7BS 7BS 8SB                                                                               0  5B 10D 0  9BS 2S  7BS                  "   1.0 +                                                                              0.25                                                                              9.5BS                                                                               0  7BS 4SB                                                                               4S  5SB 3SB                                                                               0  0  8BS 0  9BS 2S  8BS                  "   1.0 0.5                                                                               10D  0  7BS 7SB                                                                               4S  5SB 8SB                                                                               1B 3BS                                                                               9.5BS                                                                              0  9BS 2S  8BS                  "   1.0 1.0                                                                               9.5BS                                                                               0  7BS 8BS                                                                               5SB 5SB 8BS                                                                               1B 5B 10D 1S 9.5BS                                                                              1S  9SB                  "   1.0 2.0                                                                               10D  0  9.5BS                                                                              9SB                                                                               8BS 8BS 8BS                                                                               3SB                                                                               8B 9.5BS                                                                              0  9.5BS                                                                              2SB 9BS                  "   2.0 +                                                                              0.25                                                                              9.5BS                                                                               0  8BS 8BS                                                                               5SB 8BS 8BS                                                                               4B 5B 9BS 0  9BS 3BS 8BS                  "   2.0 0.5                                                                               10D  0  8BS 9BS                                                                               4B  6BS 8SB                                                                               3BS                                                                               5B 9BS 2S 9BS 4BS 9BS                  "   2.0 +                                                                              1.0                                                                               10D  0  8BS 10D                                                                               5SB 7BS 8SB                                                                               2B 7B 10D 2S 10D 4SB 8BS                  "   2.0 2.0                                                                               10D  0  8BS 10D                                                                               8BS 7BS 8SB                                                                               5B 7B 10D 3S 10D 4B  9BS                  Con-                                                                               0      0    0  0   0  0   0   0  0  0  0   0  0   0   0                    trol                                                                           __________________________________________________________________________

EXAMPLES 108-110

1-Methoxy-6-chloro-2-trifluoromethyl-1H-imidazo(4,5-b)pyridine was evaluated separately in combination with each of alachlor, atrazine, and propachlor. The evaluations were conducted under field conditions at a location in the southern coastal plain. The compounds were formulated by tank-mixing a commercial application of the respective known herbicide with an emulsifiable concentrate of the 1-methoxy-6-chloro-2-trifluoromethyl-1H-imidazo(4,5b)pyridine. The tank-mixed formulation was then applied to the soil surface immediately after planting with corn. Prior to planting, the plots had been broadcast with foxtail millet (Setaria italica) and sicklepod (Cassia obtusifolia) and disced. However, additional weed seeds, including weed seeds of each of the named species, were present as a natural infestation of the plots. The growing conditions were typical for the area. Evaluations were made of corn injury and stand reduction, also of the control of the weed species. There were three replications per treatment pattern, and the ratings were averaged for the three replications. Results are given in the following table for stand reduction.

                                      TABLE XXIV:                                  __________________________________________________________________________     COMBINATION OF 1-METHOXY-6-CHLORO-2-TRIFLUOROMETHYL-1H-IMIDAZO(4,5-b)PYRID     INE ("A")                                                                      ALACHLOR ("B"), ATRAZINE ("C"), AND PROPACHLOR ("D")                                                Percent                                                                Reduction in                                                                           Corn      Percent Weed Control                            Rate in      Emergence                                                                              Injury    Foxtail Millet Sicklepod                        Treatment                                                                            Lbs./Acre                                                                             (10 Days)                                                                              23 Days                                                                             64 Days                                                                             16 Days                                                                             24 Days                                                                             42 Days                                                                             16 Days                                                                             24 Days                                                                             42                     __________________________________________________________________________                                                             Days                   A     1.0    0       0    3    61   88   90   14   14                          "     1.5    0       0    0    33   92   98   14   0    ↑                "     2.0    9       13   17   11   100  100  0    0    NO                     "     3.0    10      17   23   56   100  100  0    0                           B     2.0    3       0    0    67   62   97   0    0    READING                A+B   0.75+0.75                                                                             0       0    0    89   83   95   14   0                           "     0.75+1.0                                                                              2       0    0    100  96   98   14   57   MADE                   "     1.0 +1.0                                                                              0       0    0    100  96   100  0    0    ↓               "     1.0 +1.5                                                                              6       0    0    94   100  100  14   71                          "     1.5 +2.0                                                                              0       0    0    100  100  100  29   0                           C     2      4       0    7    11   33   88   0    57                          A+C   0.75+0.75                                                                             0       0    0    44   79   97   0    14                          "     0.75+1 0       0    3    44   79   98   0    14                          "     1 +1   0       0    0    72   96   100  29   43                          "     1 +1.5 0       0    0    61   96   100  57   86                          "     1.5 +2 0       0    7    50   100  100  43   86                          D     5      0       0    0    72   100  95   14   0                           A+D   0.75+2 10      0    7    100  92   97   0    0                           "     0.75+3 0       0    0    100  100  100  14   29                          "     1 +2   0       0    0    100  96   100  29   29                          "     1 +3   0       0    0    100  100  100  14   0                           "     1 +5   13      0    0    100  100  100  29   0                           __________________________________________________________________________

The compounds of the present invention can also be employed as the starting materials in a reaction to prepare yet other compounds useful as herbicides. In general, this reaction comprises the treatment of one of the compounds of the present invention with a nucleophilic reagent; the reaction results in loss of the 1-OR³ moiety and introduction of the nucleophilic ion into the pyridine ring, or in reduction. Suitable nucleophilic reagents are compounds containing an amine group, in the case of those present compounds which are ethers; and compounds containing a halide ion, in the case of those of the present compounds which are esters, including the carbamate and sulfonate esters. The overall reaction scheme can be summarized as follows: ##STR11## Rearrangement is the course of reaction except where a bromide or iodide is employed, in which case, reduction occurs. The introduced nucleophilic moiety locates at either the 5 or 7 positions, depending on the identity of R² and the nucleophilic moiety.

In the instance of either reduction or introduction of the nucleophile, the products are useful, in accordance with prior teachings, as herbicides. See U.S. Pat. No. 3,459,759.

Two synthetic routes are useful in the preparation of the starting 1-hydroxy compounds: ##STR12## In a first synthetic route, the compounds are prepared by reduction of a precursor of the formula: ##STR13## The reaction is believed to go through several intermediates which are not isolatable, but yields as product the desired 1-hydroxy-1H-imidazo(4,5-b)pyridine compound. The reaction conditions are not critical; however, it is generally preferred to employ as reducing agent two moles of hydrogen per mole of the nitropyridineamine, in the presence of a minor amount of a catalyst comprising a noble metal, preferably palladium. In a representative synthesis, 1-hydroxy-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine was prepared as follows:

5-Chloro-3-nitro-2-(trifluoroacetamido)pyridine (2.0 grams) was hydrogenated with two moles of hydrogen in ethanol containing 0.5 gram of 5 percent palladium on carbon. The resulting reaction mixture was filtered and evaporated to separate the desired 6-chloro-1-hydroxy-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine compound which, after recrystallization from benzene melted at 268°-70° C.

Analysis, Calc.: C, 35.39; H, 1.27; N, 17.69. Found: C, 35.59; H, 1.45; N, 17.77.

In a second synthetic route, a suitable 1-hydroxy compound ##STR14## is itself utilized as a precursor to other 1-hydroxy compounds which serve as starting materials for the preparation of the compounds of the present invention. In this route, the initially employed 1-hydroxy compound is subjected to reactions to introduce onto the pyridine ring one or more desired groups and/or to convert one or more substituents already present on the pyridine ring to the desired group or groups.

Thus, for example, the 1-hydroxy compound can be halogenated or nitrated at a position or positions previously unsubstituted. A nitro group already present can be reduced to an amino group; and an amino group already present can also be oxidized back to a nitro group. An amino group can also be diazotized and replaced by, for example, a halo group, a nitrile group, or a loweralkylthio group. Oxidation of the loweralkylthio-substituted compound yields the corresponding loweralkylsulfonyl-substituted compound. The fluorinated groups (R² ═ --CF₃, --CF₂ Cl, or --CF₂ H) are readily obtained initially by conversion of a nitrile to a carboxyl group; subsequent treatment with SF₄ in the presence of HF yields the --CF₃ group. Alternately, conversion to an aldehyde and treatment with SF₄ alone yields the --CF₂ H group; and subsequent chlorination converts the --CF₂ H group to the corresponding --CF₂ Cl group. An alkyl substituent is introduced by reaction of an alkyl lithium with a halo-substituted 1-hydroxy compound; and a perfluoroalkyl substituent is introduced by reaction of a halo-substituted 1-hydroxy compound with a perfluoroalkyl iodide in the presence of copper. These and numerous other conversion substitution reactions are well known to those skilled in the art. Attention is directed to Fieser and Fieser, Advanced Organic Chemistry (Reinhold Publishing Corp., New York, N.Y., 1961), especially chapters 9 and 17. See also Wagner and Zook, Synthetic Organic Chemistry (John Wiley and Sons, Inc., New York, N.Y., 1953).

As will be understood by those skilled in the art, more than one of the foregoing reactions will be needed to complete the preparation of some of the compounds of the present invention; and in the case of all reactions, due consideration must be given to the orienting effect of substituent groups. Also, for those of the foregoing reactions which utilize a nucleophilic reagent, it may be necessary that the 1-hydroxy group first be converted to an ester or ether, as discussed hereinabove; and the reaction with nucleophilic reagent then conducted.

Preferred compounds of the present invention are those which are monosubstituted (n ═ 1) and the substituent (R²) is halogen, nitro, --CF₃, --CF₂ Cl, --CF₂ H, or loweralkylsulfonyl of C₁ -C₄.

A particularly preferred sub-genus of the compounds of the present invention is defined as follows: ##STR15## wherein R⁸ represents halo or --CF₃ ; R⁹ represents loweralkyl of C₁ -C₄, loweralkenyl of C₂ -C₄, benzyl, loweralkanoyl of C₂ -C₄, loweralkenoyl of C₃ -C₄, benzoyl, loweralkylsulfonyl of C₁ -C₄, or carbamoyl of the formula ##STR16## wherein X represents oxygen or sulfur, and one R⁴ represents phenyl, loweralkyl of C₁ -C₄, or loweralkenyl of C₂ -C₄, and the other R⁴ represents hydrogen, loweralkyl of C₁ -C₄, or loweralkenyl of C₂ -C₄, subject to the limitation that both R⁴ moieties taken together do not contain more than six carbon atoms, or both R⁴ moieties taken together represent straight-chain alkylene of C₂ -C₆, both inclusive; and R¹⁰ represents trifluoromethyl, pentafluoroethyl, or 1,1,2,2-tetrafluoroethyl. 

I claim:
 1. The method which comprises applying to a plant part a growth-inhibiting amount of an active agent, said active agent being a compound of the formula: ##STR17## wherein R¹ represents hydrogen, chlorine, fluorine, difluoromethyl, perfluoroalkyl of C₁ -C₆, or radical of the formula: ##STR18## wherein each Z independently represents hydrogen or halogen and m represents 0 or 1; R² represents halogen, nitro, --CF₃, --CF₂ Cl, --CF₂ H, or loweralkylsulfonyl of C₁ -C₄ ; and R³ represents(1) alkanoyl of C₂ -C₁₆ ; (2) alkenoyl of C₃ -C₁₆ ; (3) carbamoyl of the formula ##STR19## wherein X represents oxygen or sulfur; and one R⁴ represents phenyl, loweralkyl of C₁ -C₄, or loweralkenyl of C₂ -C₄, and the other R⁴ represents hydrogen, loweralkyl of C₁ -C₄, or loweralkenyl of C₂ -C₄, subject to the limitation that both R⁴ moieties taken together do not contain more than six carbon atoms, or both R⁴ moieties taken together represent straight-chain alkylene of C₂ -C₆, both inclusive; (4) radical of the formulae ##STR20## of C₁ -C₄ or ##STR21## wherein X is, as above, oxygen or sulfur; (5) radical of the formula ##STR22## wherein R⁵ represents methylene, ethylene, or vinylene, and n represents 0 or 1; (6) radical of the formulae ##STR23## phenyl, wherein substituted phenyl is a phenyl radical bearing from 1-3 substituents, each of which is independently amino, nitro, chloro, methyl, or methoxy, and R⁶ represents loweralkylene of C₁ -C₄, both inclusive; or (7) --SO₂ --R₇ wherein R⁷ is loweralkyl as above defined, cycloalkyl of C₅ -C₆, phenyl, substituted phenyl as above defined, or benzyl.
 2. The method of claim 1 wherein the active agent is 1-acetoxy-6chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.
 3. The method of claim 1 wherein the active agent is 1-octanoyloxy-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.
 4. The method of claim 1 wherein the active agent is 1-(allylcarbamoyloxy)-6-chloro-2-(trifluoromethyl)1H-imidazo(4,5-b)pyridine.
 5. The method of claim 1 wherein the active agent is 1-(methylsulfonyloxy)-6-chloro-2(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.
 6. The method of claim 1 wherein the active agent is 1-(methylcarbamoyloxy)-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.
 7. The method of claim 1 wherein the active agent is 1-(2-methoxy-3,6-dichlorobenzoyloxy)-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.
 8. The composition which comprises a surface active agent and a plant growth-inhibiting amount of an active agent which is a compound of the formula: ##STR24## ##STR25## wherein R¹ represents hydrogen, chlorine, fluorine, difluoromethyl, perfluoroalkyl of C₁ -C₆, or radical of the formula: ##STR26## wherein each Z independently represents hydrogen or halogen and m represents 0 or 1; R² represents halogen, nitro, --CF₃, --CF₂ Cl, --CF₂ H, or loweralkylsulfonyl of C₁ -C₄ ; and R³ represents(1) alkanoyl of C₂ -C₁₆ ; (2) alkenoyl of C₃ -C₁₆ ; (3) carbamoyl of the formula ##STR27## wherein X represents oxygen or sulfur; and one R⁴ represents phenyl, loweralkyl of C₁ -C₄, or loweralkenyl of C₂ -C₄, and the other R⁴ represents hydrogen, loweralkyl of C₁ -C₄, or loweralkenyl of C₂ -C₄, subject to the limitation that both R⁴ moieties taken together do not contain more than six carbon atoms, or both R⁴ moieties taken together represent straight-chain alkylene of C₂ -C₆, both inclusive; (4) radical of the formulae ##STR28## of C₁ -C₄ or ##STR29## wherein X is, as above, oxygen or sulfur; (5) radical of the formula ##STR30## wherein R⁵ represents methylene, ethylene, or vinylene, and n represents 0 or 1; (6) radical of the formulae ##STR31## phenyl, wherein substituted phenyl is a phenyl radical bearing from 1-3 substituents, each of which is independently amino, nitro, chloro, methyl, or methoxy, and R⁶ represents loweralkylene of C₁ -C₄, both inclusive; or (7) --SO₂ --R⁷ wherein R⁷ is loweralkyl as above defined, cycloalkyl of C₅ -C₆, phenyl, substituted phenyl as above defined, or benzyl.
 9. The composition of claim 8 wherein the active agent is 1-acetoxy-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.
 10. The composition of claim 8 wherein the active agent is 1-octanoyloxy-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.
 11. The composition of claim 8 wherein the active agent is 1-(allylcarbamoyloxy)-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.
 12. The composition of claim 8 wherein the active agent is 1-(methylsulfonyloxy)-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.
 13. The composition of claim 8 wherein the active agent is 1-(methylcarbamoyloxy)-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.
 14. The composition of claim 8 wherein the active agent is 1-(2-methoxy-3,6-dichlorobenzoyloxy)-6-chloro-2-(trifluoromethyl)-1H-imidazo(4,5-b)pyridine.
 15. The composition which comprises an inert finely divided solid and a plant growth inhibiting amount of an active agent which is a compound of the formula: ##STR32## ##STR33## wherein R¹ represents hydrogen, chlorine, fluorine, difluoromethyl, perfluoroalkyl of C₁ -C₆, or radical of the formula: ##STR34## wherein each Z independently represents hydrogen or halogen and m represents 0 or 1; R² represents halogen, nitro, --CF₃, --CF₂ Cl, --CF₂ H, or loweralkylsulfonyl of C₁ -C₄ ; and R³ represents(1) alkanoyl of C₂ -C₁₆ ; (2) alkenoyl of C₃ -C₁₆ ; (3) carbamoyl of the formula ##STR35## wherein X represents oxygen or sulfur; and one R⁴ represents phenyl, loweralkyl of C₁ -C₄, or loweralkenyl of C₂ -C₄, and the other R⁴ represents hydrogen, loweralkyl of C₁ -C₄, or loweralkenyl of C₂ -C₄, subject to the limitation that both R⁴ moieties taken together do not contain more than six carbon atoms, or both R⁴ moieties taken together represent straight-chain alkylene of C₂ -C₆, both inclusive; (4) radical of the formulae ##STR36## of C₁ -C₄ or ##STR37## wherein X is, as above, oxygen or sulfur; (5) radical of the formula ##STR38## wherein R⁵ represents methylene, ethylene, or vinylene, and n represents 0 or 1; (6) radical of the formulae ##STR39## phenyl, wherein substituted phenyl is a phenyl radical bearing from 1-3 substituents, each of which is independently amino, nitro, chloro, methyl, or methoxy, and R⁶ represents loweralkylene of C₁ -C₄, both inclusive; or (7) --SO₂ --R⁷ wherein R⁷ is loweralkyl as above defined, cycloalkyl of C₅ -C₆, phenyl, substituted phenyl as above defined, or benzyl. 